A new type controller based on DSP and adaptive control is developed to synchronously switch 10 kV reactive power compensation capacitor banks for reducing transients. The controller based on digital signal processor TMS320F206 and 6-channel simultaneous sampling A/D chip ADS7864 realizes real-time measurement of active power and reactive power and tracks voltage zero points; an adaptive algorithm is adopted to minimize the affects of drifts of actuator’s operating time for closing shunt capacitor banks at the voltage zero point and opening at the current zero point. The test results show that the synchronous controller is reliable and works smoothly. And it can be connected with substation and dispatching automation system to realize reactive power control.