Lateral shear interferometers have large measurement range and good anti-disturbance ability. They have similar accuracy compared with the reference based interferometers. Based on a specially designed shear generator, a new lateral shear interferometer is proposed. The new system has a complete common optical path and a simple mechanism. The optical model of the interferometer is presented and the anti-vibration characteristics are analyzed. To validate its antivibration ability for on-machine surface measurement, experimental tests have been conducted and results presented.