The function of the controller is to adjust the rise and fall of the ground shovel constantly according to the signal of positional deviation transmitted from the laser receiver, and remove or fill in the soil of the farmland, thus reaching the aim of smoothing the farmland. So the controller is the core component of the laser-control-ground system. The speed of response and the control algorithm of the controller are in relation to the stability and work efficiency of this system. This research uses the RS485 module to transmit, enhancing the interference immunity of the system, raising the stability when it works in severe environment, replacing SCM with CPLD to carry out the function of logical control, cutting down the power consumption of the system. It interferes manually in the hydraulic control automatic mode via software, thus improving the stability and flexibility of the system. The function of adjusting the duty cycle of the controller output signal is added, making the controller able to work both in paddy field and dry land.