Bone marrow stroma stem cells (BMSSCs) have shown promising future in repairing injured myocardium. However, few studies have explored the potential mechanism of BMSSCs transplantation for dilated cardiomyopathy (DCM). In this study we aimed to examine whether BMSSCs transplantation can improves the cardiac function of dilated cardiomyopathy of rats and investigate the possible mechanism of BMSSCs transplantation improving the cardiac function of dilated cardiomyopathy according to investigate the collagen fiber deposition, capillary density, VEGF and its receptor expression. Global heart failure in Wistar rats was induced by means of adriamycin administration, after labeled with DAPI, BMSSCs were transplanted into the myocardium of rats which were divided into transplantation group and control group. At 1w, 2w, 3w, 4w after transplantation, heart function was measured by hemodynamic, the deposition of collagen fiber, expressions of VEGF and its receptor and capillary density were checked by immunochemistry and RT-PCR. Immunofluorescence microscopy revealed that the transplanted BMSSCs were visible at four weeks after transplantation. Compared with the control group, the transplantation group had a significantly higher maximum rate of rise and decline (?dp/dt) of left ventricular pressure and left ventricular systolic pressure (P < 0.05), as well as a significantly lower rate of left ventricular diastolic pressure (P < 0.05). The deposition of collagen fibers in the myocardium of transplantation group was reduced, according to A value in transplant group is less than control group (P < 0.05). The expression of VEGF and its receptor were significantly higher than those of control group, and the upregulation of VEGF and its receptors was unsynchronized, the capillary density is higher in transplantation group than control group after four weeks. Taken together, our results suggest that BMSSCs transplantation can improve dilated cardiomyopathy's heart function of rats, we found that BMSSCs transplantation prevented the fusion of collagen fibers to some extent, decrease the deposition of collagen fiber and maintained the orderly structural arrangement of myocardial tissue. BMSSCs transplantation can also promote the angiogenesis, in our study we found that capillary density increased, BMSSCs transplantation not only upregulated the expression of VEGF, but also upregulated the expression of VEGF receptors. Unsynchronized upregulation of VEGF and its receptors was observed which may promote angiogenesis continuously and steadily.