In recent years, high frequency errors of mirror surface are taken seriously gradually. In manufacturing process of advanced telescope, there is clear indicator about high frequency errors. However, the sub-mirror off-axis aspheric telescope used is large. If uses the full aperture interferometers shape measurement, you need to use complex optical compensation device. Therefore, we propose a method to detect non-spherical lens based on the high-frequency stitching errors. This method does not use compensation components, only to measure Aperture sub-surface shape. By analyzing Zernike polynomial coefficients corresponding to the frequency errors, removing the previous 15 Zernike polynomials, then joining the surface shape, you can get full bore inside tested mirror high-frequency errors. 330mm caliber off-axis aspherical hexagon are measured with this method, obtain a complete face type of high-frequency surface errors and the feasibility of the approach.