Abstract: It is supposed that the X-ray pulsar-based navigation method (XPNAV) can provide high-precision navigation throughout the solar system, and its utility on the heliocentric transfer orbit was discussed. The search space array method was introduced to resolve integer pulse phase cycle ambiguities between the nominal position and estimated position of the spacecraft. A description of blending the vehicle dynamics with the pulse phase differences at nominal and estimated spacecraft locations within an Kalman Filter was provided for recursive determination of vehicle position and velocity. The simulation illustrates that this method is feasible and effective for interplanetary missions.