import arcpy

mxd = arcpy.mapping.MapDocument("current")  #获取当前打开的文档
layers = arcpy.mapping.ListLayers(mxd)   #获取当前的图层组
#对图层进行循环处理
for layer in layers:
	arcpy.AddField_management(layer,"name","TEXT","#",50)   #添加名称为name的字段
	fieldArrays=arcpy.ListFields(layer)    #获取字段列表
	arcpy.DeleteField_management(layer,fieldArrays[2].name)  #删除原来排第二个不需要的字段
	data = layer.name.split('_')[0]    #获取需要的内容
	arcpy.CalculateField_management(layer, "name", '\"'+ data + '\"', "VB", "")   #对name字段赋值