Abstract: The X-ray pulsar-based navigation (XNAV) technology is to determine the attitude,position and velocity of spacecraft using X-ray signals emitted from pulsars. The feasibility and sustainability of pulsar navigation is invented through theoretical astrometric analyses. The processing and modeling of pulsar signals of both X-ray and radio band is introduced,and then investigate The key problems in pulsar navigation are analyzed,and finally the applicable range of distance of XNAV is discussed. The our analyses show that the acquiring of the measurements is highly influenced by the spacecraft velocity. With the error of less than 3 m/s,the profile of a pulsar signal can be got,and from which the time of arrival (TOA) could be obtained. Also,the phase cycle ambiguity is a non-negligible problem in pulsar navigation.