Based on the development trend of the power market in which the retail market and the spot market converge, we analyze the profit model of the electricity retailer under the spot market mode, construct a market power monitoring model of the electricity retailer, and study the specific scenarios of the electricity retailer's market power implementation in the retail market under the spot market mode, so as to provide a reference for the monitoring of the electricity retailer's implementation of market power behaviors under the spot market mode, which will be further conducive to the effective convergence between the retail market and the spot market, as well as to the healthy operation of the power market.