In high power laser system, a small size phasedistortion wavefront measure is necessary to compensate and control the wavefront of laser beam with intermediate frequency. Array Fresnel zone plates splitting wavefront and the Southwell model of zonal wavefront reconstruction arithmetic are presented, the effect of the sub-apertures of wavefront sensor and variation range of distorted phase on wavefront reconstruction are analyzed in detail, and a suitable number 20×20~30×30 of array Fresnel zone plates is given. Simulation results show the error of wavefront reconstruction with this method is small than one-tenth wavelength.