Abstract: In order to solve the positional accuracy difference of plane data and the low calculation precision of plane model's constant term, a robust plane fitting method based on least squares-weighted total least square (LS-WTLS) was proposed. This method uses least squares model and robust estimation of IGGⅢ scheme to calculate the error parameters of plane model. Meanwhile, after rejecting the gross error data by setting the threshold, the constant term of plane model was calculated by using least square model. And based on this model, the accuracy of plane parameters was further improved. The new method shows favorable resistant to gross errors in experiments of fit the simulated plane data, meanwhile, the observed plane data fitting experiments show that compared with LS method, TLS method, LS-TLS method, IGGⅢ-LS-TLS method, the new method's mean square error of unit weight increased by 53.6%, 195.0%, 47.5%, and 5.1%, respectively, and its plane fitting accuracy increased by 53.6%, 195.0%, 47.5%, and, 5.1%, respectively. The results effectively verify this new method's superiority and reliability in the field of plane fitting.