To get performance of attainable end point accuracy of long range navigation, error factors influencing precision were analyzed, and a precision analyzing method using simplified dynamical model together with ��quasi-mean�� element and covariance method was put forward, mathematical models of error propagating and analyzing were deduced, simulation was carried out based on mathematical models presented. The results show that end point accuracy of long range navigation is mainly affected by error propagation, and that position and velocity errorscan be controlled below 5?km and 3?m/s respectively under certain initial circumstances when propagating time is less than ��6?h��. Along-track error and radial error are main error factors in error propagating and along-track error becomes larger as propagating time becomes longer, therefore improving end point accuracy along-track error and radial error must be mainly restrained. Accuracy analyzing method introduced above considers comprehensively various error factors and is convenient and quick. It is suitable for engineering utilizing in scheme design phase.