NIAOT has made a stressed lap polishing machine and finished aφ 910mm, F/2.0 paraboloid. In the process we found shape control strategy is an important technology for stressed lap polishing tool and this kind of content has not been discussed systematically before. So this paper mainly dedicates to the method of lap shape control. Firstly a mathematical model of stressed lap is introduced. Then three shape control methods are put forward one by one concerning aspects as shape accuracy and deformation hysteresis. The fundamental method is least square algorithm. On the base of it we put forward its reformation form: least square algorithm with damping factor. To get more satisfied performance a new algorithm using optimization under constrains of linear inequalities is proposed. Through theoretical analysis and computer simulation some comparisons are made among three methods. Finally we have done experiments

using stressed lap polishing machine in NIAOT and the results obtained substantiate the feasibility and efficiency of our method.