In order to correct the distortion of C-arm projection image,a moving least squares combined with polynomial fitting global correction method was proposed.The pincushion distortion,S distortion and local distortion were considered as a whole and moving least squares was used to increase virtual control points for its compact support.The composite distortion was fitted by Nth polynomial and the images were corrected with optimum correction coefficients obtained by the least square method.The result demonstrates that the proposed method could achieve higher precision with less control points than only with global polynomial fitting,and the actual space error is 0.1054±0.068mm which means it is possible to apply the corrected images in surgery navigation.