Abstract: There often encounter ill-conditioned problem of navigation constellation for autonomous orbit determination by using the inter-satellite link, so orbit determination of constellation can not be achieved directly using EKF algorithm. For distributed autonomous orbit determination model, the divergent reasons of EKF algorithm are analyzed through the thought of biased estimation. Thus the ridge-type EKF algorithm is first proposed by using the combination of ridge estimate and EKF algorithm, and a specific method is given for the determination of ridge parameter. Finally, Walker24/3/1 constellation is simulated by STK and distributed autonomous orbit determination is implemented. The validity of ridge-type EKF algorithm is verified by the results of simulation example.