To promote the construction of a unified national power market system and form a diversified competitive power market environment, it is necessary to clarify the regional electricity market modes which can be coordinated with the operation of national, regional, provincial markets. Based on the typical transaction patterns under the framework of regional competitive electricity trades, five typical regional competitive electricity trade modes are summarized and analyzed. Besides, the corresponding market operation mechanisms, social welfare, characteristics and advantages and disadvantages of different models are analyzed. Theoretical analysis and modeling calculation results indicate that the "single market, two-tier clearing" mode and the "single market, unified clearing" mode will have the same efficiency only under several certain conditions. From the perspective of social welfare, the "single market, unified clearing" mode is better to be chosen as the goal for regional unified power market construction. Moreover, a social welfare redistribution mechanism that matches the "single market, unified clearing" model is proposed, providing decision-making reference for the orderly promotion of the construction of a unified power market.