Satellite Laser Ranging system is an accurate and complicated system integrated with light, mechanism and electric. Main control system controls the emission, reception of ranging signal and processes the ranging data through laser system, telescope system and optics system. It is the key technique to secure the high automation and high success odds of the satellite laser ranging system. It uses FPGA to design the signal control board, generates the laser trigger signal and range gate signal, to control Laser, SPAD and event timer accurately. The paper designs the function modules through analyzing the whole working process of the system in detail. The controlling test to 1 meter telescope and laser, the data process test with the real daylight satellite ranging data, all show good effects.