On-axis TMA (Three Mirror Anastigmatic) is a popular form used in lightweight high resolution space-borne camera. Mirrors of on-axis TMA are often aspherical

whose surface accuracy are influenced by environment and manufacturing. Environment endurance is decided by structure design

and manufacturing is connected to time and cost. So

every factor should be synthesized and analyzed to ensure the designed resolution of optical system

and do not lead to any waste. Take some actual on-axis TMA system with a Φ600mm primary mirror for example

surface irregularity influence to Gaussian focus wave-front error is analyzed

and mathematic expression of the influence is acquired.. Circle field fixed Zernike polynomial is used as a opt-mechanic interface to analyze the environment influence on primary mirror and system performance degeneration. Taking the result as reference

supporting structure of primary mirror is improved. Based on the Marechal criterion and environment endurance

the manufacturing accuracy of primary mirror is deduced

which should precede λ/36.5.