A four-end beam structure piezoresistive accelerometer with high sensitivity and small size is designed in this paper. The structure with different cantilever beam and mass block sizes is modeled using finite element software, and sensitivity and stress analysis, modal analysis, and dynamic response are performed on the structure. The simulation results show that the axial sensitivity reaches 7.40μV/g, the lateral sensitivity is 0.33%, the linearity is 0.06%, the response time is 20.3μs, and the natural frequency is 111.2kHz within the 50000g range. The impact resistance can reach 334000g, which can satisfy the test needs in a high-g environment, and this research provides an accurate and efficient simulation method for the development of high-performance sensors.