Abstract: Method,model and software of AOD(autonomous orbit determination) of navigation satellites by using least square collocation method has been introduced in this paper based on cross-link ranging observations and the prior information provided by forecasting ephemeris.Series of simulations through self-developed software has discussed the influence of measurement noise,residual systematic error of observations and the quality of prior information to precision of AOD.Results indicated that measurement noise contributes less obvious influence on AOD precision,while effects of residual systematic error and the prior information are more distinct,which need to be considered seriously in practical application.