The coupling characteristics and channel model of the carrier signal in the medium voltage buried cable are the basis for analyzing the transmission characteristics. Based on the principle of electromagnetic induction, combined with the coupling mode of the snap-in inductive coupler and the structure of the medium-voltage buried cable, the coupling model of the snap-in inductive coupler is derived. Then, according to the actual medium voltage distribution network topology and cable grounding method, the multi-conductor transmission line theory and the branch addition method are used to construct the channel model of the carrier signal in the medium voltage buried cable. Finally, based on the channel model, the transmission characteristics of the carrier signal in the conductive layers of the medium voltage buried cable and the total transmission characteristics of the different locations are analyzed, and the simulation and laboratory tests are carried out. The results show that the carrier signal has the same transmission characteristics in the three-phase cable core; the carrier signal strength is the largest in the armor layer, the shielding level is the smallest, and the three-phase cable core is the smallest; the carrier signal strength will have an attenuation of about -15dB for each time through the ring network cabinet. This work is supported by National Natural Science Foundation of China (No. 51807063) and Fundamental Research Funds for the Central Universities (No. 2019MS081).