Abstract: This paper involves a kinematic surveying system project which consists of two components, a mobile data acquisition and a post mission data processing. The latter includes GPS receiver, INS (intertial navigation system), CCD camera and barometer, etc. Correspondingly, the method and software for the data processing and image matching are more important than the first part. INS especially provides the short term stable observation of the bearing. Based on the T-U-V filter, a linear, unbias and minimum variance smoothing formula has been presented. According to the raw data, the method has been derived to preprocess INS bearing data. After smoothing calculation of different window sizes have been performed and compared, a preprocessing accuracy of 0.01° has been reached.