Abstract: The lightweight structure of honey-comb holes on the back of the sphrical reflector of spaceborne sensor is discussed in this paper. A computer program for differentiating elements, generating nodes and automatically building up files of finite element models is worked out. The structure under the selfweight load condition is computational analyzing with structural analysis program and a series of data of maximum deformation are derived on the premise of variation of relevant structure parameters.The data are fitted into curves and farthermore the experiential formula of optimal solution of the lightweight structure is deducted.