ZnO thin film was prepared by atomic layer deposition （ALD） and furtherly used as the carrier transport layer of thin film transistors. The phototransistor was fabricated and used in photo detection by combining the ZnO with particular CsPbBrI₂ all inorganic perovskite to form hybrid film because of its excellent optical properties. ZnO thin film in the transistors could be prepared at relatively low temperature of 150 ℃ without furtherly high temperature annealing， and simultaneously the CsPbBrI₂ perovskite films could also be formed by a low temperature process. The photodetector exhibited a good response to the light in a wide wavelength range between 365 nm and 600 nm. When exposed to the light irradiation of 500 nm wavelength， the optimized responsivity of 2×10³ A/W and detectivity of 3×10¹⁴ Jones were achieved， respectively. The transient response of CsPbBrI₂/ZnO phototransistor also delivered a rise time of 250 ms and a fall time of 200 ms， and there remained ultra-high stability in the transient behavior even after a long-time measurement.