The construction of HVAC/HVDC transmission channels and the development of the inter-provincial and inter-regional power market are advancing steadily in China. However, there is no research on the optimal power distribution calculation of the HVAC/HVDC transmission channels under the power market environment. A two-stage HVAC/HVDC transmission channel power optimal distribution method under the medium and long-term power market environment is proposed. In the first stage, according to the protocol electricity, the cooperative calculation between the optimal scheduling of intra-region generation and transmission and the optimal power distribution of HVAC/HVDC transmission channels is realized by using the alternating direction method of multipliers. In the second stage, according to the market increment electricity, the transmission channel power distribution scheme adjustment model is established. The final HVAC/HVDC transmission channel power distribution scheme is obtained through two-stage distribution calculation. Simulation results of a three-region HVAC/HVDC hybrid system verify that the proposed method can achieve the reasonable power distribution of transmission channels under power market environment.