In the context of an increasingly complex international political and economic situation, major powers have promoted the formation of regional trade agreements of various forms and scope. The impact of MTAs on regional economic growth is explored in this topic, using the Regional Comprehensive Economic Partnership Agreement (RCEPA) as an illustration. Through mathematical modeling and quantitative assessment, a general equilibrium model of the impact of a multivariate trade agreement on regional economic development has been constructed. Different regions and industrial sectors related to the agreement are delineated, and different simulation scenarios are designed to assess the impact of MTAs on regional economic growth under different scenarios. The results show that the members and non-members of the MTA under different simulation scenarios are positively and negatively impacted to varying degrees, with Japan, Australia, and New Zealand among the RCEP members experiencing the most significant positive stimulus, with GDP growth of 3.95%, 2.89%, and 2.11%, respectively. Non-members had a negative impact on the scale of imports and exports and terms of trade, with the United States and India shrinking by 1.16% and 1.69%, respectively. Overall, the MTA contributes positively to the development of regional economic growth.