In order to meet the coupling communication requirements of the carrier signal in the medium voltage distribution network cable line, a clamp inductive coupler with a high coupling efficiency is required. This paper proposes a clamp inductive coupler coupling model of medium-voltage distribution network carrier and analyzes its coupling efficiency. Firstly, the coupling mechanism of the clamp inductive coupler is analyzed on the basis of the structure type of the clamp inductive coupler and the structure of the cable circuit; then, the coupled mathematical model of the clamp inductive coupler is deduced in combination with the Rogowski coil and the loose-coupling transformer model, and the mutual inductance is modified. The mutual inductance coupler is used to construct a simulation using ansoft electromagnetic software to verify the correctness of the deduced coupled mathematical model of the clamp inductive coupler. Finally, the different effects of the clamp inductive coupler are analyzed using the coupler mathematical model and simulation model. The effect of the air gap of the coupler ring, the relative permeability of the ring, the number of winding turns, and the frame size of the coupler on the voltage coupling efficiency at the cable side is analyzed. The simulation results and calculation results show that the mathematical model of the coupled coupler can accurately reflect the coupled state of the coupler, which provides a good analysis method and theoretical basis for the practical application of the power line carrier technology in the intelligent distribution network. This work is supported by National Natural Science Foundation of China (No. 51807063) and Fundamental Research Fund for the Central Universities (No. 2019MS081).