Abstract: To insure the security of space mission, the dangerous big debris must be tracked and predicted. Firstly, the computing model of standard orbit is given in this paper. Secondly the coordinate transformation from True Equator and Mean Equinox of Date to Earth Mean Equator and Equinox of Date which two-line mean element (TLE)used is provided. And Simplified General Perturbations Version 4 and Simplified Deep-space Perturbation (SGP4/SDP4)which developed from analytic orbital theory are introduced. Then according to the typical orbits, the precision of SGP4/SDP4 is analyzed. The result shows that SGP4/SDP4 are efficient and valid to the initial prediction of danger.