Herein, we used Cd34-CreER;Rosa26-tdTomato mice, an inducible lineage tracing model, to trace the fate of CD34+ cells in TAC (transverse aortic constriction)-induced myocardial remodeling, then combined with single-cell RNA sequencing (scRNA-seq) technique and bone marrow transplantation model; our results showed that non-bone-marrow-derived CD34+ cells are the major source of fibroblasts and endothelial cells in the process of myocardial fibrosis. The gene discussed is CD34; the disease is Myocardial fibrosis.