The difference of in-line particle hologram are shown mainly for different laser wavelength.The hologram of the particle field is influenced by the microparticle diameter and particle density.These two parameters may even determine the quality of the measurement.Therefore,these two parameters are mainly discussed for different laser wavelength through numerical simulation.The interference fringes of microparticle are enlarged by infrared laser and easy to resolve.Simultaneously,the transmissivity of infrared laser through the high density object field is larger than green laser and verified by experiment.All results confirm the dominance of infrared laser in-line particle holography.