This paper designs a highvoltage amplifier suitable for driving piezoelectric actuator based on selfdeveloped highprecision digital phaseshift interferometer. This amplifier adopted the way of DC coupling between lownoise, nonchopperstabilized lowvoltage amplifier circuit and highvoltage amplifier circuit, and combined with feedback network, power amplifier circuit, filter circuit and current limiting protection Circuit. The amplifier circuit is mainly consist of OP07 opamp and the power transistors (MJE340&MJE350). The range of 0 V to 5 V low input voltage produced by the computer is stably amplified into the -30 V to+130 V. Output ripple peak is as low as 10 mV .Thus, the highvoltage amplifier has better stability satisfying the requirements of driving control of the piezoelectric ceramic phase shifter and the high accuracy requirement for the interferometer.