Abstract: This article explores how to effectively connect medium-and long-term trading with spot trading in the development of the electricity market, as well as the important role of phased trading. The article explains how to guide users from the traditional monthly unified electricity price model to a more flexible 24-hour electricity price model by introducing a time of use electricity price mechanism. This article proposes a spot market retail time of use user settlement model. The model first settles based on the monthly total electricity consumption, and after calculating the accurate electricity bill, uses the difference between the two settlement results to perform a margin adjustment operation, aiming to improve the accuracy and efficiency of electricity bill settlement. The article provides a digital system design case for calculating retail time of use user electricity bills, demonstrating the practical application of this settlement model. The application has proven that the innovation of this settlement model is conducive to promoting the implementation of time of use trading mechanism, stimulating users to actively participate in load regulation, and providing practical cases for building a new type of power system.