For the demand of high precision and long life of the scanning mechanism used for space optical remote sensing instrument,the design of lubrication and sealing of the space bearing was studied.Considering thermal effect and nonNewtonianism of greases,the mathematical model for angular contact space ball bearing was established,and the numerical solution was got.The effect on lubrication of each parameter was analyzed,and the optimized method of lubrication was put forward.By analyzing the sealing effect of clearance seal,a better sealing structure was presented. Results show that thermal effect,nonNewtonianism and high load as well as low entrainment velocity can result in the decrease of film thickness.Combined clearance sealing structure can effectively decrease the leakage of greases compared with straight through type clearance sealing structure.