Abstract: In order to achieve the goal of “carbon peaking and carbon neutrality”, General Secretary Xi Jinping proposed to build a power system with new energy as the main body. It is one of the important ways to realize the goal of “double carbon” to establish a new power system market trading mode for low-carbon energy transition. Therefore, a two-level inter-provincial-intra-provincial market transaction model and a clearing optimization model were proposed. First, the paper analyzed the characteristics of high proportion of clean energy access, high proportion of cross-regional power transmission and high proportion of flexible resource regulation under the new power system and described its market trading framework. Secondly, the provincial market transaction with new energy as the main body was designed, including annual bilateral negotiation/centralized bidding transaction, monthly bilateral negotiation/centralized bidding transaction, monthly (multi-day) transaction and auxiliary service transaction. Inter-provincial transaction mode was designed, including annual/monthly inter-provincial and inter-regional transaction, inter-provincial electricity purchase transaction, clean energy delivery transaction and inter-provincial peak regulation auxiliary service transaction. On the basis that the balance between supply and demand of electricity is satisfied, the day-ahead market clearing model aiming at the maximum consumption of clean energy in the province and the day-ahead market clearing model aiming at the minimum total cost were constructed. Finally, a new power system in a province was taken as an example to simulate day-ahead and day-day market trading under typical scenarios. The results show that the proposed market trading mode effectively promotes the consumption of clean energy, slows down the occurrence of wind and light abandonment, power rationing and other phenomena, and promotes the realization of the " double carbon " goal.