IGeoDataset pGeoDataset = dataset as IGeoDataset;//dataset可为FeatureClass或FeatureDataset
ISpatialReference spatialReference = pGeoDataset.SpatialReference;
if (spatialReference is IProjectedCoordinateSystem){
    IProjectedCoordinateSystem2 projectedCoordinateSystem=spatialReference as IProjectedCoordinateSystem2;
    string strSpheroidName = projectedCoordinateSystem.GeographicCoordinateSystem.Datum.Spheroid.Name;//获取椭球名称
    string strProjectionName=projectedCoordinateSystem.Projection.Name;//投影名称
    double dblScaleFactor=projectedCoordinateSystem.ScaleFactor;//尺度因子
    double dblLatitudeOfOrigin=projectedCoordinateSystem.LatitudeOfOrigin;//纬度原点 
    OriginProjectionSetting.strCentralMeridian = Convert.ToString(LidfSurveyFunctions.DegreeToDms(projectedCoordinateSystem.CentralMeridian[true]));//*子午线
    OriginProjectionSetting.XAdditiveConstant = projectedCoordinateSystem.FalseNorthing;//北坐标加常数
    OriginProjectionSetting.YAdditiveConstant = projectedCoordinateSystem.FalseEasting;//东坐标加常数
    //…………………………等等参数
}else {//is IGeographicCoordinateSystem
    IGeographicCoordinateSystem geographicCoordinateSystem=spatialReference as IGeographicCoordinateSystem;
    string strSpheroidName = geographicCoordinateSystem.Datum.Spheroid.Name;
    double dblSemiMajorAxis = geographicCoordinateSystem.Datum.Spheroid.SemiMajorAxis;  //椭球长半轴
    //…………………………等等参数                                  
}