In order to realize tunable longwave infrared laser, we design a ZGP temperature tuned longwave infrared optical parametric oscillator. A Ho:YAG laser with the center wavelength of 2097 nm is used to pump ZGP crystals with different phase matching angles. The temperature adjustable properties of ZGP-OPO is researched by changing the operating temperature of crystal. The laser with a segment continuously tunable range of 7.53-8.77 μm is realized in the temperature range of 15-30°C, with a total tuning range of 1.24 μm. The output power of ZnGeP₂-Optical Parametric Oscillator(ZGP-OPO) is greater than 1.503 W over the entire tuning range. The output power is 1.503 W at the idler wavelength of 8.77 μm, and the corresponding slope efficiency and optical conversion efficiency are 12.19% and 6.53%, respectively. The experimental results show that temperature tuning of ZGP is an effective technical method to obtain continuously tunable long-wave infrared laser. This research has potential application value in the field of engineering of tunable long-wave laser.