The invention relates to a servo control signal compensation method. The method includes the following steps that: a structural strength test system simulation model is built, wherein the structural strength test system simulation model includes a servo valve control compensation model, a servo valve model, an actuation cylinder model and a test piece model, wherein the servo valve control compensation model comprises a control object part , a PID control equipment model part and compensation rules for carrying out compensation on servo valve control signals; a simulation structural strength test is carried out; compensation rules of the servo valve control signals are obtained through simulation; and an actual structural strength test is carried out, programming is carried out in a signal control channel outputted by a PID control device, simulation is written, the compensation rules can be obtained, and calculation and output are carried out. According to the servo control signal compensation method of the invention, PID parameters are not changed, signals, namely servo valve control signals, which are outputted by the PID control device are compensated in real time, and therefore, the PID control device can adapt to constantly-changing test conditions, and load control error can be lowered.