方法一：

    /// <summary>
    /// 实体属性处理
    /// </summary>
    public class PropertyHandle
    {
        #region 反射控制只读、可见属性
        //SetPropertyVisibility(obj,   "名称 ",   true); 
        //obj指的就是你的SelectObject，   “名称”是你SelectObject的一个属性 
        //当然，调用这两个方法后，重新SelectObject一下，就可以了。
        /// <summary>
        /// 通过反射控制属性是否只读
        /// </summary>
        /// <param name="obj"></param>
        /// <param name="propertyName"></param>
        /// <param name="readOnly"></param>
        public static void SetPropertyReadOnly(object obj, string propertyName, bool readOnly)
        {
            Type type = typeof(ReadOnlyAttribute);
            PropertyDescriptorCollection props = TypeDescriptor.GetProperties(obj);
            AttributeCollection attrs = props[propertyName].Attributes;
            FieldInfo fld = type.GetField("isReadOnly", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.CreateInstance);
            fld.SetValue(attrs[type], readOnly);
        }

        /// <summary>
        /// 通过反射控制属性是否可见
        /// </summary>
        /// <param name="obj"></param>
        /// <param name="propertyName"></param>
        /// <param name="visible"></param>
        public static void SetPropertyVisibility(object obj, string propertyName, bool visible)
        {
            Type type = typeof(BrowsableAttribute);
            PropertyDescriptorCollection props = TypeDescriptor.GetProperties(obj);
            AttributeCollection attrs = props[propertyName].Attributes;
            FieldInfo fld = type.GetField("browsable", BindingFlags.Instance | BindingFlags.NonPublic);
            fld.SetValue(attrs[type], visible);
        }
        #endregion
    }

举例：比如某个实体类TestEntity中有自增列（IdentityColumnInfo）这么一个属性，该自增列对应的实体类如下：

public class IdentityColumnEntity 
    {
        private bool isIncrementColumn;
        /// <summary>
        /// 是否是自增列
        /// </summary>
        [Browsable(true)]
        [Category("基本")]
        [DisplayName("是否是自增列")]
        [ReadOnly(false)]
        [DefaultValue(false)]
        public bool IsIncrementColumn
        {
            set { isIncrementColumn = value; }
            get { return isIncrementColumn; }
        }

        private Int64 identityIncrement;
        /// <summary>
        /// 标识增量
        /// </summary>
        [Browsable(true)]
        [Category("基本")]
        [DisplayName("标识增量")]
        [ReadOnly(false)]
        [Description("标识增量属性指定在 Microsoft SQL Server 为插入的行生成标识值时，在现有的最大行标识值基础上所加的值。标识增量必须是 非零 整数，位数等于或小于 10。")]
        public Int64 IdentityIncrement
        {
            set { identityIncrement = value; }
            get { return identityIncrement; }
        }

        private Int64 ident_Seed;
        /// <summary>
        /// 标识种子 
        /// </summary>
        [Browsable(true)]
        [Category("基本")]
        [DisplayName("标识种子")]
        [ReadOnly(false)]
        [Description("指示标识列的初始行值。标识种子必须是  整数，位数等于或小于 10。")]
        public Int64 Ident_Seed
        {
            set { ident_Seed = value; }
            get { return ident_Seed; }
        }       
    }

实体类TestEntity代码如下：

  public class TestEntity
    {
        private IdentityColumnEntity identityColumnInfo;
        /// <summary>
        /// 是否自增列
        /// </summary>
        [Category("扩展信息")]
        [DisplayName("自增列信息")]
        [ReadOnlyAttribute(true)]
        [XmlIgnore]
        [Browsable(true)]
        //[XmlAttribute]
        public IdentityColumnEntity IdentityColumnInfo
        {
            get
            {
                if (identityColumnInfo != null && identityColumnInfo.IsIncrementColumn)
                {
                    PropertyHandle.SetPropertyReadOnly(identityColumnInfo, "Ident_Seed", true);
                    PropertyHandle.SetPropertyReadOnly(identityColumnInfo, "IdentityIncrement", true);
                    PropertyHandle.SetPropertyReadOnly(identityColumnInfo, "IsIncrementColumn", true);
                    PropertyHandle.SetPropertyReadOnly(this, "IsInsert", true);
                    PropertyHandle.SetPropertyReadOnly(this, "IsUpdate", true);
                }
                return identityColumnInfo;
            }
            set
            {
                identityColumnInfo = value;
            }
        }

        /// <summary>
        /// 是否插入
        /// </summary>
        [Category("维护信息")]
        [DisplayName("是否插入")]
        [ReadOnlyAttribute(false)]
        [XmlAttribute]
        public bool IsInsert
        {
            get
            ;
            set
            ;
        }

        /// <summary>
        /// 是否更新
        /// </summary>
        [Category("维护信息")]
        [DisplayName("是否更新")]
        [ReadOnlyAttribute(false)]
        [XmlAttribute]
        public bool IsUpdate
        {
            get
            ;
            set
            ;
        }
    }

通过 PropertyHandle.SetPropertyReadOnly即可实现，效果如下：

演示源码：点击打开链接

本文参考： 如何在设计时中动态改变控件属性在PropertyGrid中显示出来的只读性

小注：

如何修改自定义属性的显示问题呢？

方法二：即参考文章中提到的：Unleash PropertyGrid with Dynamic Properties and Globalization

源码及演示demo下载：点击打开链接