Pericytes, specialized mural cells residing within the basement membrane of pulmonary microvessels, participate in various biological processes, including vascular homeostasis, immunomodulation, and tissue repair. However, these beneficial physiological roles can be detrimental under pathological conditions. Numerous pulmonary fibrosis models have demonstrated pericyte differentiation into scar-forming myofibroblasts, leading to collagen deposition and matrix remodeling, thereby contributing to tissue fibrosis. Similarly, pericytes play crucial roles in inflammatory diseases. This review aims to explore the dual roles of pericytes in the lung and the underlying mechanisms of their role conversion, providing insights for developing therapeutic strategies targeting these cells.