直接贴代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Winform2
{
    public partial class Form1 : Form
    {
        public float Xvalue;
        public float Yvalue;
        bool flag = false;
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            foreach (Control control in this.Controls) {
                control.ForeColor = Color.Red;
            }
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            if (flag) {
                float newx = (this.Width) / Xvalue;
                float newy = this.Height / Yvalue;
                setControls(newx, newy, this);
            }
        }

        private void setControls(float newx, float newy, Control cons)
        {
            foreach (Control con in cons.Controls)
            {
                string[] mytag = con.Tag.ToString().Split(new char[] { ':' });
                float a = Convert.ToSingle(mytag[0]) * newx;
                con.Width = (int)a;
                a = Convert.ToSingle(mytag[1]) * newy;
                con.Height = (int)(a);
                a = Convert.ToSingle(mytag[2]) * newx;
                con.Left = (int)(a);
                a = Convert.ToSingle(mytag[3]) * newy;
                con.Top = (int)(a);
                Single currentSize = Convert.ToSingle(mytag[4]) * newy;

                //改变字体大小
                con.Font = new Font(con.Font.Name, currentSize, con.Font.Style, con.Font.Unit);

                if (con.Controls.Count > 0)
                {
                    try
                    {
                        setControls(newx, newy, con);
                    }
                    catch
                    { }
                }
            }

        }

        private void Form1_Load(object sender, EventArgs e)
        {
            Xvalue = this.Width;
            Yvalue = this.Height;
            flag = true;
            setTag(this);
        }

        private void setTag(Control cons)
        {
            foreach (Control con in cons.Controls)
            {
                con.Tag = con.Width + ":" + con.Height + ":" + con.Left + ":" + con.Top + ":" + con.Font.Size;
                if (con.Controls.Count > 0)
                    setTag(con);
            }
        }
    }
}

窗口加载两个事件即可。

一个是加载onload事件：用于获取窗口的长和宽的

一个是窗口大小Resize改变事件：当窗口大小改变时触发的事件