Pulsars are rapidly rotating neutron stars that generate pulsed electromagnetic radiation.A new method for intersatellite relative position determination between a global navigation satellite system(GNSS) and spacecraft using X-ray pulsars is proposed in this paper.The geometric model of this method is formulated,and two different resolution algorithms are introduced and analyzed.The phase cycle ambiguity resolution is investigated,and a new strategy is proposed and formulated.Using the direct vector parameters of the pulsar,geometric dilution of precision(GDOP) is studied.It is shown that this method has advantages of simplicity and efficiency,and is able to eliminate the clock errors.The analytical results are verified numerically via computer simulations. Pulsars are rapidly rotating neutron stars that generate pulsed electromagnetic radiation. A new method for intersatellite relative position determination between a global navigation satellite system (GNSS) and spacecraft using X-ray pulsars is proposed in this paper. The geometric model of this method is formulated , and two different resolution algorithms are introduced and analyzed. The phase cycle ambiguity resolution is investigated, and a new strategy is proposed and formulated. Using the direct vector parameters of the pulsar, the geometric dilution of precision (GDOP) is studied. It is shown that this method has advantages of simplicity and efficiency, and is able to eliminate the clock errors. The analytical results are verified numerically via computer simulations.