High-orbit optical surveillance platform has advantages accepting state information of space-objects. The orbit determination theory for space objects and its precision assessment methods by high-orbit optics surveillance platform were analyzed. The accuracy of three kinds of space objects based on high-orbit optics surveillance platform was studied.The orbit determination accuracy was assessed by two methods of observation residuals and results’ covariance and the reliability of results was demonstrated and the effects of orbit determination caused by the error in the measurement were studied. Simulation experiment shows that the orbit determination precision for those space objects reaches kilometer level. System error is the main source of orbit determination errors.