ZnGeP2 crystal has several absorption peaks in 1 μm to 2.5 μm, which are mainly caused by point defect VP, GeZn and VZn. These optical absorption seriously affect the applied performance in optical parametric oscillator. Therefore, theoretical calculation of electron irradiation based on the electron-nucleus scattering theory were executed to understand the effective experiment condition. The ZnGeP2 single crystal was grown by Bridgman method, then the infrared absorption spectrum, Hall coefficient and carrier concentration of as grown ZnGeP2, annealed ZnGeP2 and irradiated ZnGeP2 were tested by infrared spectrometer and physical performance mearsurement system. The results show that annealed treatment can effectively reduce the optical absorption of ZnGeP2 crystal near 1.2 μm and 1.4 μm, while electron irradiation treatment is beneficial to reduce the optical absorption of ZnGeP2 crystal near 2.0 μm, which is consistent with the calculated results.