A tunable metal/medium/metal type(MDM) near-infrared optical surface absorber based on Ge2Sb2Te5(GST) phase change material is proposed to realize active regulation of infrared absorption wavelength. Firstly, the absorption performance of the device is calculated and analyzed by using the finite difference time domain(FDTD) method. Then, the physical mechanism of plasma shock absorption of the absorber is analyzed according to the electric field distribution characteristics. The simulation results show that the absorption peak center position of the proposed absorber is shifted from 1.17 μm to 1.8 μm, and the deviation width is 630 nm. When the appropriate crystallization fraction of GST is selected, the absorber can achieve a high-low absorptivity conversion at a communication wavelength of 1.55 μm.