Abstract: The factor of altitude is not fully considered in traditional path loss models, which cannot be applied to the air-to-ground communication scenarios directly. Based on the ray tracing technique, this paper proposed a statistical path loss model for air-to-ground mmWave channels. This model derived the path probabilities of four different propagation cases, i.e., line-of-sight, reflection, diffraction and no signal, and comprehensively took the influences of environment, frequency, distance, and antenna height into account. The simulation and analyze show that the proposed model has good applicability for different scenes and antenna heights. The classification of non-line-of-sight makes its calculation results of path loss more accurate than the ones of traditional models, and more consistent with the results of ray tracing method. It can be used in the system design and algorithm optimization of air-to-ground millimeter-wave communication systems.