To design high resolution remote camera optical system,this paper researched the issues in the during of the design of reflective optical system,proposed the three-mirror-anastigmat (TMA) optical systems of field bias,full field and annular field according to fields distributing,and finished its optical system design which was characterized by the spectrum band of 500-800 nm,focal length of 6000 mm and F number of 10. The result indicates that the image quality of the optical system approaches or reaches the diffraction limit,which can meet the demand for use of high resolution space cameras. Through analyzing and comparing the difficulty in fabricate and assembling of the three kinds of the three-mirror-anastigmat optical systems,it can be a special reference to the design of other large aperture and long focal length space telescope.