Thanks!
I found the reason.
I need add
#version 120
#extension GL_EXT_gpu_shader4 : enable
at the top of floorshadow vertex shader file.
Although, floor shader works, the floor disappeared. My code seems too messy, many problems:)
Finally, I implemented shadow mapping on floor.
I should not uncomment gl_Position = ftransform().
But, I still found shadow formed by many isolated dark points.
I don’t know this effect is correct or not.
I attached the image.