The surface-profile precision of lens is a main factor which influences the performance of the optical system.There are three main reasons which influence the lens surface-profile most, and they are the supporting structure, gravity and thermal load.In order to achieve the goal of getting high surface-profile precision of the lens (Φ>200 mm), a new multi-points flexible supporting structure is designed.Then, the influence of gravity and thermal load with the designed structure is analyzed.The results are as follows: for the deformation caused by gravity, the surface root-mean-square (RMS) value is 6.78 nm and 3.46 nm for the upper and lower surface respectively; for the deformation caused by thermal load, the surface (RMS) value is 8.30 nm and 5.57 nm for the upper and lower surface respectively.The designed structure with multi-point flexible support can effectively reduce the influence of precision loss which is caused by gravity and thermal load, and meet the requirements of high surface-profile precision of large-aperture lens for transmission-type optical system(RMS<λ/50, λ=632.8 nm).