Exploring the coupled coordination between regional economic high-quality development and ecological environmental protection is the basis for integrating the promotion of high-quality development and high-level ecological protection. Based on the data of Heilongjiang Province from 2010 to 2022, the coupling coordination model and decoupling model were used to measure the coupling coordination degree and decoupling index between the two systems. The results show that the index of high-quality economic development in Heilongjiang province shows a fluctuating upward trend, and the index of ecological environmental protection steadily recovers after experiencing a significant decline. The degree of coupling and coordination between the two systems generally shows a rising trend, but there is still a gap with the state of high-quality coupling and coordination. Heilongjiang Province has experienced the decoupling state transition of “strong negative decoupling-expansive negative decoupling-weak decoupling” at various stages, and the decoupling state is great, while only a few years of each prefectural-level city have reached the ideal decoupling state. Based on the conclusions, countermeasures are proposed to promote the synergistic development of regional economic quality and ecological environment.