A THz UM-MIMO channel estimation method based on the DCNN comprises the steps: the hybrid spherical and planar-wave modeling (HSPM), by taking a sub-array in the antenna array as a unit, employing the PWM within the sub-array, and employing the SWM among the sub-arrays; estimating the channel parameters between the reference sub-arrays at Tx and Rx through a DCNN, including the angles of departure and arrival, the propagation distance and the path gain; deducing the channel parameters between the reference sub-array and other sub-arrays by utilizing the obtained channel parameters and the geometrical relationships among sub-arrays, and recovering the channel matrix; wherein accurate three-dimensional channel modeling is achieved by the HSPM, which possesses high modeling accuracy and low complexity.