In order to reduce inrush current and over-voltage which caused by random switch capacitors during reactive power compensation in coal mine power network,this paper designs a kind of reactive power compensation device based on promising "soft switch" technology that is phase-controlled switching technology, takes long life, low cost vacuum contactors with permanent magnetic actuator as switching ,this actuator has little action time dispersion than traditional spring actuator and electromagnetic actuator, in order to meet action time high degree of consistency, this paper compensates vacuum contactors action time dispersion, uses modular ideas to design reactive power compensation system structure diagram,together with the appropriate control strategy, completion the capacitor bank switching at a predetermined phase.finally this system makes experiment test in certain mine coal 6KV power network,experiment results show that phase-controlled switching technology of reactive power compensation effect is unmatched by traditional others methods, practice proved that this system has a certain value.