Aiming at the problem that the tracking accuracy of the three variable controller ( TVC), which requires high precision of the controlled model, is reduced due to the influence of system parameter changes and external interference on the loading test bench of electro-hydraulic damping damper. An adaptive three variable controller ( ATVC) was proposed, with a model reference adaptive control (MRAC) to compensate the loading system into an ideal stable reference model, and then an adaptive three variable control strategy was applied to the ideal reference model. According to the theoretical model of electro-hydraulic loading system of damping damper, the transfer function of the loading system considering the damping of the damping damper under test was derived. The model reference adaptive control system was designed based on Diophantine equation polynomial, and the loading system was compensated to realize the ideal reference model with non-minimum, which improved the system stability. The natural frequency and damping ratio of the loading system with a stable ideal reference model were compensated by three-state feedback, and pole assignment was realized by three-state feedforward to improve the dynamic characteristics of the system. Through the position step and sine response tests of the three-state control and the adaptive three-state control, under the action of the position square wave loading signal of 2.0 mm / 10 Hz, the overshoot was 13.5% and 9.6% , respectively, decreasing 28.9% , and the rise time was 7.4 ms and 5.8 ms respectively, decreasing 21.6% . The steady-state errors were 0.030 mm and 0.018 mm, respectively, which were decreased by 40.0% . Under the position sinusoidal loading signal of 1.5 mm / 30 Hz, the displacement errors were 0.29 mm and 0.18 mm, respectively, which were decreased by 37.9% . The adaptive three-state control can obviously improve the transient performance index and displacement tracking accuracy of the electro-hydraulic servo loading test bench.