This study takes Yunnan as an example to analyze the coupling coordination relationship between economic development and rural poverty reduction at county-level from 2010 to 2015 and investigates its forming mechanism via analytic hierarchy process, coupling coordination model and Lorenz Curves. Results indicate that the county-level economy in Yunnan had been developing rapidly from 2010 to 2015 and showed a low-level imbalance pattern with a remarkable polarization. During the study period, the incidence of poverty in rural areas of Yunnan declines dramatically but the imbalanced spatial pattern remains significant. There form a low-value area centering around the economic development pole and high-value areas centering around the remote mountain areas of Wumeng Mountain as well as the northern and southern border areas in western Yunnan. Due to the negative correlation between the economic development and the incidence of rural poverty, the relationships between county-level economic development and rural poverty reduction in 2010 and 2015 all showed a slight imbalance, and the coupling coordination status in 2015 was lower than that in 2010. The concurrent average annual growth rate of economic development and the annual slowdown of the incidence of rural poverty are on the brink of imbalance. This is mainly because the correlation between those two are negative under low-level demand combined with the islanding effect of the distribution of the poor, which reduces the poverty reduction effect. In the process of promoting the implementation of the targeted poverty alleviation policy, the accuracy of policies should be strengthened from many aspects on the basis of economic development, so as to realize the goal of poverty alleviation in 2020 as well as to provide a good foundation for the rural vitalization and a moderately prosperous society in an all-round way.