Crucial requirements were proposed on the Primary Mirror Assembly(PMA), such as high lightweighting, high stiffness, high stability and short manufacturing cycle. In order to satisfy those, a meniscus-like mirror lightweighting scheme based on ZERODUR was designed, and the flexural support structure bonded to the outer ring of the mirror shaft was optimized. Through a finite element analysis and design approach, the optimal dimensions of the flexural support were obtained. In order to verify the finite element analysis results, a modal test was performed on the PMA, and the required aspherical optical surface was polished and tested. Test results show that, the first natural frequency of PMA is 332.5 Hz, the relative deviation is only 2.5% to compare with the analysis result; the surface figure of PMA maintains a constain RMS of λ/40 while rotating at 0°, 120° and 240° around the horizontal optical axis respectively; the influence of zero-gravity state is achieved on surface figure of PMA. The PMA satisfies the design requirements.