In order to solve the problem of unified settlement of the electricity retail company, this paper conducts an in-depth analysis of the underlying logic of electricity retail unified settlement, sorts out the key factors of unified settlement in the electricity retail market, designs a mathematical model of unified settlement, and proposes the application of the settlement model in the power market technical support system. Finally, the feasibility and superiority of the model are verified by an example. The outcomes solve the unified settlement connection between the electricity wholesale market and the electricity retail market of the electricity retail company, and fully embodies the freedom, flexibility, and complexity of retail settlement in a fully competitive electricity market. The unified settlement model supports the efficient and accurate execution of electricity retail settlement work, and guarantees the realization of the goal of the electricity retail-side reform.