In order to counteract the transmission line capacitance effect relatively accurate based on the reactive power state of the system，this paper designs a kind of parallel digital reactor which can output the required perceptual reactive power smoothly according to the power system real-time reactive state. This digital reactor changes the inductive current which flows through the reactor’s inductance coil by controlling secondary side voltage inverter to offset the grounding capacitive current. DSP is used as CPU which is cooperated with CPLD and ADC to control the inverter output PWM. The experimental results show that digital reactor that has the advantagesof simple configuration，rapid response and wide range continuously of inductance change to reached well to adjust the action of making power penetration line reactive power balance.