Until now, no effective solution is proposed to detect the wavefront of a longfocus and largediameter lens. To solve the problem, combining Talbot effect and Moiré fringe, a new method, which utilizes twodimensional scanning to detect the subaper ture wavefront, is proposed. The optical path is improved and a prototype is established after considering both precision and complexity of engineering. In this method, the subwavefront slope is obtained by twodimensional scanning. The wavefront is reconstructed by mode method based on Zernike polynomials and singular value decomposition method. Compared the experimental results with the measurements of WYKO laser interferometer, the method is validated and the precision of the prototype is acceptable in practical applications.