In response to the urgent demand for high g-value accelerometers in aerospace, vehicle collision analysis and other fields, a new multi-beam groove piezoresistive accelerometer was designed, which used variable section beams as sensitive beams to amplify the equivalent inertial force of the mass, and effectively improved the structural stiffness through the combination of auxiliary beam and back groove to achieve high sensitivity output and good bandwidth characteristics. The mechanical model of the accelerometer was established, and the structure and size of the accelerometer were optimized through ANSYS finite element software. Using the surface path of the sensitive beam, the stress distribution law was analyzed and summarized, and the varistor position was determined. The simulation results demonstrate that the designed sensor measurement range was 150 000 g, and the sensitivity was 1. 32 μV/ g, and the natural frequency was about 268 kHz. Based on SOI technology, the processing flow of the accelerometer was finally designed.