In satellite navigation channel simulator, the traditional pseudo-range Doppler simulation method has some flaws, such as the low delay accuracy and the large filter resource. A new Doppler simulation method is proposed, using Lagrange interpolation variable fraction delay filter and Farrow structure. Based on analyzing the system architecture of channel simulator, the model of Doppler simulation was established, including the delay calculation module and variable delay filter. Compared with the multi-rate sampling digital delay filter method, the proposed method is just about 0.2% of the former filter resource, and the one parameter is just changed when the delay of filter is changed. Actual measured results with channel simulator indicate that the Doppler accuracy is 0.1 mHz.