【Abstract】 Objective To investigate the application value of functional multislice CT perfusion imaging of VX2 tumor in rabbit by monitoring the radiotherapeutic effect before and after radiotherapy. Methods To select twenty-four Japan white rabbits which are implanted VX2 tumor successfully and divide them into two groups (sixteen per group) at random. To perform MSCT perfusion scan two weeks after implantation and one week after radiation therapy respectively. Then to obtain mean values of blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface (PS) of VX2 tumors and to analyze the differences among them. Results There is no statistical significance compared parameters including BF、BV、PS of radiation treatment group to control group pre-radiation therapy(P＞0.05). There is statistical significance compared parameters including BF、BV、PS of radiation treatment group to control group post-radiation therapy(P＜0.01).Perfusion parameters including BF、BV、PS are decreased post-radiation therapy compared to control group or radiation treatment group pre-radiation therapy and there is significant differences between them(P＜0.01). Conclusions MSCT perfusion imaging is able to reflect hemodynamic changes of VX2 implanted breast tumor, which can evaluate the early radiotherapy effect in malignant breast tumor invasively and accurately.