Against the dual backdrop of rapid urban development and the drive to build an ecological civilization, coordinating industrial growth with ecological protection is crucial for the sustainable development of industrial cities. Using Haining—a typical industrial city—as a case study, this paper analyzes land-use and landscape-pattern evolution with five phases of land-use/land-cover data (1980, 1990, 2000, 2010, and 2020) and constructs an ecological security evaluation system. The results indicate that (1) under policy influences, multiple land types in Haining tended to convert into urban–rural residential construction land; (2) over the past forty years, the landscape pattern became more optimized, and ecological security improved, with increased diversity alongside reductions in fragmentation and contagion; and (3) the overall ecological security level rose significantly during the same period. Sustained macro-level policy regulation is needed to maintain long-term ecological security in industrial cities. The study shows that Haining’s ecological security is closely linked to landscape patterns, land-use change, and human disturbance. By tailoring development strategies for different stages, ecological security and sustainable development can be effectively supported, offering guidance for Haining and industrial cities worldwide.