The manufacture of transmission optics beam expander used in Hartmann wavefront detection system was introduced. Based on the third-order aberration theory,the reasons why off-axis aberrations can't be well corrected for traditional beam expander were analyzed.Submitting the primary parameters to optical design software of ZEMAX,a new type of beam expander which can perfectly correct the on-axis and off-axis aberrations is designed.It provided with wide aperture,large relative aperture and large field of vision. According to the actual demands of Hartmann beam expander,a concrete design example is presented,and corresponding mechanical design is matched for it. The ways of fabrication,adjusting and testing are introduced too.