Abstract: Combine harvester is important for harvesting agricultural products.Forward speed has a great impact on efficiency of combine harvester.Feeding amount will decrease with decrease of forward speed.It is very important to effectively control walking speed of combine harvester.Walking speed control system of combine harvester was put forward.Through theoretical basis，the model and working principle of walking speed control system of combine harvester were discussed.The hardware design of control system included hydraulic control system，single chip microcomputer system and system I/O port expansion.Circuit design of control system included signal acquisition circuit，display system circuit and output control circuit.