A new type of charge-sensitive three-stage amplifier was developed. The circuit design mainly adopted an ADA4817 high-speed and low-noise integrated operational amplifier chip. The three-stage amplifier had low noise, good stability, a simple circuit structure, high cost performance, and ease of maintenance. It could amplify signals with rise time in nanoseconds without distortion, and the output signal quality of the amplifier was excellent. It was used with a multi-channel analyzer MCA8000D to read a single photoelectron spectrum of a microchannel plate (MCP) assembly or a single channel electron multiplier (CEM). The test results show that the custom-made amplifier fully satisfied the pulse performance test requirements of MCP or CEM detectors, and its technical indicators were close to those of imported A250 amplifiers.