Magnetic resonance imaging (MRI) is an important diagnostic method for the breast cancer. However, for conventional MRI techniques such as diffusion-weighted imaging (DWI), it ignores the non-Gaussian behaviors of the water diffusion caused by the restriction of tissue microstructure, thus the conventional method is insensitive to microstructural and heterogeneity changes in breast tumor. This study explores the feasibility of applying a continuous-time random-walk (CTRW) non-Gaussian diffusion model to the differentiation and assessment of malignant and benign breast tumors. The correlations between CTRW parameters and breast tumor immunohistochemical features such as oestrogen receptor (ER), progesterone receptor (PR) and Ki67 expression status are studied. The CTRW model has potential in future applications of breast tumor malignancy and therapeutic efficacy evaluation.