To solve the capacitive accelerometer sensitivity low, cross sensitivity higher performance problems, we design a new quality of three pieces of three axis MEMS capacitive accelerometer, the quality of three piece of accelerometer to measure the X, Y, Z three orthogonal axes and acceleration, separate horizontal (X, Y axis) and vertical axis (Z axis) accelerometer integrated on the same SOI wafer, Low cross sensitivity and high displacement sensitivity are achieved by parallel bonding on the glass substrate. The mathematical model of the accelerometer structure was analyzed and established, and the structure and size of the accelerometer were optimized through COMSOL simulation analysis. The displacement sensitivity of the three mass blocks accelerometer in the vertical axis direction was 1. 536 69 μm/ g, and the displacement sensitivity in the horizontal axis was 6. 78 μm/ g, and the cross sensitivity was all less than 1%.