The distribution probability of the photon interarrival time (PIT) without signal initial phases is derived based on the Poisson model of X-ray pulsar signals,and a pulsar signal detection algorithm employing the PIT sequence is put forward.The joint probability of the PIT sequence is regarded as a function of the distribution probability and used to compare a constant radiation intensity model with the nonhomogeneous Poisson model for the signal detection.The relationship between the number of detected photons and the probabilities of false negative and positive is studied,and the success rate and mean detection time are estimated based on the number of the given photons.For the spacecraft velocity data detection,the changes of time of photon arrival (TOPA) and PIT caused by spacecraft motion are presented first,then the influences on detection are analyzed respectively.By using the analytical pulse profile of PSR B0531+21,the simulation of the Xray pulsar signal detection is implemented.The simulation results verify the effectiveness of the proposed method,and the contrast tests show that the proposed method is suitable for the spacecraft velocity data detection. The distribution probability of the photon interarrival time (PIT) without signal initial phase is derived based on the Poisson model of X-ray pulsar signals, and a pulsar signal detection algorithm employing the PIT sequence is put forward. The joint probability of the PIT sequence is regarded as a function of the distribution probability and used to compare a constant radiation intensity model with the nonhomogeneous Poisson model for the signal detection. The relationship between the number of detected photons and the probabilities of false negative and positive is studied, and the success rate and mean detection time are estimated based on the number of the given photons. For the spacecraft velocity data detection, the changes of time of photon arrival (TOPA) and PIT caused by spacecraft motion are presented first, then the influences on detection respectively.By using the analytical pulse profile of PSR B0531 + 21, the simulation of the Xray pulsar signal detection is implemen ted. The simulation results verify the effectiveness of the proposed method, and the contrast tests show that the proposed method is suitable for the spacecraft velocity data detection.