The utility model relates to a precise alternating current amplifier which can carry out high-accuracy real-time equal-proportion amplification on standard alternating current, and has good amplitude gain stability and phase stability. The precise alternating current amplifier comprises an input output port, a current amplifying circuit, a direct current clamping circuit and a high frequency filter circuit, wherein the current amplifying circuit forms an alternating current negative feedback loop through an operational amplifier, a transformer and a current transformer, and achieves high-accuracy amplification of a standard alternating current source in a work frequency band, the direct current clamping circuit is composed of an integrating circuit and a lowpass filter circuit and is used for eliminating nonlinear influences when the transformer and the current transformer work with direct current, and the high frequency filter circuit is used for preventing the current amplifying circuit from oscillation. The precise alternating current amplifier has the advantages of low cost, real-time response, high accuracy, isolation of a current output loop, high power utilization rate, and the like.