The utility model relates to an entry driving machine cut arm automatic speed adjustment system belongs to colliery extractive equipment application technique field. The utility model discloses a cut motor, in the current sensor, PLC controller and electro -hydraulic proportional valve, current sensor detects cut power of motor state, and will detect signal output to PLC controller, through the analysis of PLC controller, calculate, output control signal, through proportional amplifier with the signal amplification, then control electro -hydraulic proportional valve regulated stream flow, realize control cutting units vertical lift hydraulic cylinder and level gyration hydraulic cylinder's swing speed, change the cutterhead load through adjustment hydraulic cylinder swing speed, thereby realize the permanent power output of cut motor. This control system can be according to the load of load automatically regulated cut motor, is applicable to the tunnel working face of the different hardness of cut, has solved to transship the structure and electric component damage that leads to because of the cut motor. The utility model discloses in can be used to driving machinery or other motor drive hydraulic control device, there is very big application prospect.