X-ray pulsar based navigation (XNAV) can provide spacecrafts with autonomous positioning service. The accuracy of standard XNAV is coarse, in addition to that the pulsar timing model error and clock error can cause an approximate static bias in measurement error. Simulation results shows that 2 pulsars are needed to achieve total observability when using XNAV alone; and only 1 pulsar is needed when using integrated navigation with XNAV and cross-link measurement. Integrated navigation can also improve the positioning accuracy by over 10 times, and limit the estimation error caused by the static bias to under 0.2 meters. With realistic noise settings, using only standard XNAV in orbit estimation, a positioning accuracy within 50 meters can be acquired with only 2 pulsars. When using integrated navigation with cross-link measurement, the single pulsar navigation plan can achieve a positioning accuracy of 5 meters, proving that integrated navigation with single pulsar in standard XNAV is an autonomous navigation method with high precision, low requirement and relatively easier to implement.