Abstract: A new algorithm was studied to satisfy exterior trajectory data pre-treatment. The algorithm not only provided an effective method to real-time data processing but also had low computational cost. It was an adaptive outlier removal algorithm, which had good adaptability for radar data and photoelectric theodolite data. The standard deviation of the five successive test data was multiplied by three and the product was taken as threshold. The new method of calculating the dynamic threshold could complete real-time outlier removal of exterior trajectory data. Matlab simulation and measured data analysis proved that the proposed algorithm could completely removed isolated outlier. It is suitable for real-time exterior trajectory data processing.