An active deformable lens with small coupling error is designed to meet the requirement of astigmatism compensation because of non-uniformed illumination in lithographic objective lens. The capability of the active deformable lens is studied. The finite element model is established. Based on the finite element model, adjustment ability, rigid movement error, natural frequency and maximum stress of the active deformable lens are analyzed. Analytic results indicate that the active deformable lens is able to regulate root mean square (RMS) 837 nm astigmatism compensation Z5 with 50 N drive force. The high order aberration only is RMS 1.124 nm. The rigid movement error of translation and rotation are 0.49, 0.52, 0.13 nm, 2.21, 1.73，1.10 ms, the first order natural frequency is 2555 Hz, and the maximum stress of lens is 0.852 Mpa. The active deformable lens satisfies the requirement of astigmatism compensate in lithographic objective lens.