High-quality n-ZnO thin films were deposited on the surface of p-GaA s epitaxial wafer by pulse laser deposition technology to construct the n-ZnO/p-GaAs heterojunction photodetect ors.X-ray diffraction (XRD) and scanning electron microscope (SEM) results show that the ZnO thin films with high crystalline quality on GaAs are obtain ed.Under reverse bias,the detectors exhibit good near-infrared detection performance.With the bias cha nging from －0.5V to －4V,the spectral response curves indicate that all the responsivity peaks appear near 850nm.And when the reverse bias is －2V,the responsivity near 850nm reaches the saturation value of 10.17A/W.However,the specific detectivity reaches peak value of 2.06×10¹⁰ cm Hz1/2/W,and then dec reases with the reverse bias increasing.The spectral response curves and the specific detectivity curves under reverse bias exhibit strong selectivity for the near-infrared light in the vicinity of 850nm (with FWHM of 30nm).