Abstract: Robust vehicle tracking algorithm is an important precondition for realizing traffic event detection,but occlusion is a key influence factor for vehicle tracking．An adaptive vehicle tracking algorithm based on spatial temporal Markov random field(be short for ST-MRF)model was proposed to deal with the problem .This tracking algorithm is used to acquire the object maps and the motion vector maps．The traffic parameters can be obtained from the object maps and the motion vector maps．Then using the camera calibration technique gets the real time speed,as well as the vehicle motion coordinates．At last,through the analysis of the three parameters of traffic flow,the real-time traffic flow operation characteristics are got,which can provide basis for the traffic incident detection in the future.

Key words: ST- MRF,Vehicle tracking algorithm,Traffic parameter,Object maps,Motion vector maps