Abstract： Objective With comparative study of MR perfusion-weighted imaging characteristics and parameters change both before and after three-dimensional conformal radiotherapy, supposed to provide experi-mental basis for evaluation of PWI in measurement of effect on rabbit models of hepatic VX2 tumors. Methods New Zealand rabbits, were implanted in liver with VX2 tumor by tissue block, were divided randomly into radio-therapy and control group, PWI were performed both before and after the radiotherapy for the two groups. Select the ROI of the VX2 tumor center, tumor border and paratumor parenchyma. Maximal signal reduction slope (SRSmax)of the signal intensity versus time curves were created as quantitative variable. Analysis the laws of SRSmax decline levels of different ROI. Results The SRSmax of tumor center and tumor border of treatment group by 3 DCRT were lower than before radiotherapy (P < 0. 05) ;there were statistical significance. Conclusion PWI reflects the microcirculation and hemodynamic changes of rabbit models of hepatic VX2 tumors by 3DCRT. SRSmax can be used as a live evaluation of tumor microvascular indicators.