Abstract: The effects of shielded cable on the voltage surge for motor equipments were studied, the influencing factors of breaking motor overvoltage were analyzed, and the inductance and capacitance parameters of dedicated shielded cable for shearer were calculated with the electromagnetic theories, the electrical parameter calculation model of shielded cable is established. The results and analysis showed that the shielded cable was more effective to reduce voltage surge than the ordinary cable, but the amplitude of the voltage surge decrease was limited. In order to improve the effect of surge suppression, the shielded cable with a high relative dielectric constant insulating layer should be chosen as the power supply cable for mechanical and electrical equipment as far as possible in coal mine.