Based on reviewing the previous literature and excavating the essence of vulnerability, this paper proposed a theoretical framework that is generally applicable to ecosystem vulnerability, and then the evolution model was constructed from the perspective of the coupling between human and environment to explore the evolution mechanism of eco-environmental system vulnerability in petrochemical bases. The study finds that ecosystem vulnerability is derived from pressure disturbance. It is reflected in the combined effects of exposure and sensitivity, and ultimately depends on the state that resilience copes with impact. As a multi-level closed-loop system, petrochemical base is disturbed by various pressures, and the interactions among exposure, sensitivity and resilience determine the evolution of system vulnerability. Internal and external human and environmental factors are potential drivers of vulnerability, and the increase in pressure sources, exposure ratio and sensitivity, the degradation of resilience and lack of environmental governance capacity are concrete features that exacerbate vulnerability. Finally, taking Lianyungang petrochemical base as an example, the evolution process of system vulnerability is simulated, and the evaluation index system is built from the aspects of pressure, exposure, sensitivity, self-recovery and artificial repair capacity. The conclusions and suggestions in this paper not only have implications significance for the sustainable development of underdeveloped areas where the petrochemical base is located, but also provide theoretical basis for the further evaluation of the eco-environmental system vulnerability.