In recent years, with the construction of UHV power grid and the promotion of smart grid, inter-regional energy transactions in China has achieved rapid development, the market is becoming more active and the scale of inter-regional energy transactions is expanding further. With the steady improvement of power market supervision system, inter-regional energy transactions not only need to meet higher requirements in cost control, but also meet higher requirements in specification operation. In addition, considering the factors such as the mass access of clean energy, energy saving and emission reduction, the formulation of transactions policy needs to balance economic benefits, social benefits and normative. All various factors above have made the formulation of transactions policy turn to be more complex. It is hard to meet the requirements for the collective operation and the lean management of the inter-regional power trade completely depending on human arrangements. Therefore, it is high important to research aided optimization decision in inter-regional transactions. In this article, the author submits an inter-regional trade optimization model based on price zone. In the model, the particular technical and institutional constraints of electric systems and electricity market are considered, and the optimization of economic benefits or comprehensive benefits is the objective of transactions strategy. An example is founded based on actual data for electricity market operation. Optimal strategy in organization mode of transactions is decided through solving the model. The optimal economic benefits in different organization mode of transactions are compared, and organization mode of transactions that achieves maximum economic benefits is proposed, and the main factors affecting the benefits of transactions are analyzed. The example proves that the model can realize inter-regional trade model comparison, quantitative analysis of the energy purchase cost, the optimization of energy purchase decision, and the cohere of economic benefits, social benefits and normative.