Simple Summary Idiopathic pulmonary fibrosis is a global disease with unknown etiology. At present, there is still a lack of effective treatment methods, and more in-depth research on this disease is urgently needed. Based on this, we aim to summarize the molecular mechanism and pathological changes of different cell subsets in IPF lung, and review the latest progress of various pro-fibrotic signal transduction pathways in fibrosis, so as to provide key cells and pathways for future research on pulmonary fibrosis, propose more meaningful research directions, and provide theoretical basis for the study of idiopathic pulmonary fibrosis. It is of great significance to understand the pathological mechanism and the prevention and treatment of the disease. The respiratory system is a well-organized multicellular organ, and disruption of cellular homeostasis or abnormal tissue repair caused by genetic deficiency and exposure to risk factors lead to life-threatening pulmonary disease including idiopathic pulmonary fibrosis (IPF). Although there is no clear etiology as the name reflected, its pathological progress is closely related to uncoordinated cellular and molecular signals. Here, we review the advances in our understanding of the role of lung tissue cells in IPF pathology including epithelial cells, mesenchymal stem cells, fibroblasts, immune cells, and endothelial cells. These advances summarize the role of various cell components and signaling pathways in the pathogenesis of idiopathic pulmonary fibrosis, which is helpful to further study the pathological mechanism of the disease, provide new opportunities for disease prevention and treatment, and is expected to improve the survival rate and quality of life of patients.