This paper describes a GPS trajectories post-processing method based on velocity-time series.The method proposed needs no other input than the most basic GPS raw data:longitude,latitude and time information.First,trajectories are segmented and each stage's autocorrelation is tested to determine whether data drift occurred in this stage.Second,the velocity-time series are used to identify the drift point.Third,Spline Interpolation Method is used to correct the drift point.This procedure is applied to GPS rec...