Abstract: In existing large-scale three-dimensional multiple-input multiple-output (3D MIMO) systems, the distance between adjacent antennas may be very large, which often causes physical propagation delay when electromagnetic waves pass through the array aperture, which is called spatial broadband effect. Most scholars usually ignore it when it comes to studying channel estimation. Only when scholars study radar systems, the spatial broadband effect is mentioned. Last year, some scholars introduced it into the 2D MIMO millimeter wave system. Based on this, this paper extends it to the millimeter wave large-scale 3D MIMO system. Based on the horizontal and vertical angles of the planar antenna array, a new channel is designed. Model, and proposed a channel estimation algorithm, the simulation results show that it has good channel estimation performance.