Abstract: The construction of a new electric power system with new energy resources as the main body points out the direction of China's power transformation and development under the dual-carbon target background. However, because the cost and output characteristics of new energy resources are significantly different from those of the traditional generators, the spot market mechanism of a power system designed for the thermal power is no longer suitable for the development requirements of the new electric power system. Therefore, this paper proposes a new mechanism for new energy bidding. The new energy submits a U-shaped curve that decreases first and then increases with the output in each period. It reflects the cost characteristics with zero marginal cost, decreasing average cost and fluctuating output of the new energy. Accordingly, the coupling mechanism of the thermal power spot market and the capacity market is proposed to adapt to the new power system. However, this bidding curve makes the clearing model non-convex. Therefore, a spot market clearing model based on the non-convex quotation is creatively proposed in this paper with a series of 0-1 variables introduced, which skillfully transforms it into a solvable mixed integer programming model through the coupling relationship between the different quotation segments. Case study verifies the effectiveness of the mechanism and model proposed in this paper.