The trajectories of weakly-constrained, non-cooperative targets are massive, complex, and has real-time feature.Traditional trajectory analysis and processing technology is difficult to play an effective role here, thus we propose a technology for preprocessing the weakly-constrained, non-cooperative target trajectories.The model for cleaning the outliers, missing points and redundant points is studied.A dimensionality reduction method for trajectories is proposed based on the constraints of speed and course change rate.The reduction and expansion methods are adopted to increase the diversity of trajectory data.The simulation results show that:1) The compression rate of the processed trajectory is 64.44%, the accuracy loss is only 26.71%, and the data set is expanded by 3 times;2) High-quality trajectory data is obtained;and 3) The sensitivity of the model to the trajectory characteristics is reduced, and the models generalization capability is improved.