The effective supply of ecological products is the foundation for realizing the value of ecological products. Evaluating the regional ecological product supply capacity helps to identify the direction and path for achieving effective supply. This study seeks to clarify the concept of ecological products, to define the connotation and theoretical mechanism of ecological product supply capacity, and to construct an assessment framework for regional ecological product supply capacity. Taking Jiangxi Province as an example and applying the GIS spatial analysis and the entropy weight method, this paper also analyzes the regional ecosystem service functions, evaluates the regional ecological product supply capacity at the prefectural level, and explores strategies for improving regional ecological product supply capacity. Results show that there is still significant room for improvement in the ecological product supply capacity of Jiangxi Province. Even in Ganzhou, which has the largest resource area, the evaluation index of ecological product supply capacity is only 71.07. From 2010 to 2020, the ecological product supply capacity of various prefectural-level cities has improved to varying degrees, mainly due to the enhancement of social resource allocation capacity. Compared to Ganzhou, Xinyu, Yingtan, Pingxiang, Jingdezhen, and Nanchang have lower ecological product production capacity, while Shangrao, Ji’an, and Yichun, which have medium-level ecological product production capacity, still have significant room for improvement in their social resource allocation capacity. Therefore, based on the identification of the shortcomings in the ecological product supply capacity of each prefectural-level city, this research suggests targeting division of ecological product supply type zones, combining proactive government and effective market, and promoting green and low-carbon development.