Breast cancer diagnosis and treatment are important healthcare issues in the Industrialized World. In this study, magnetic resonance imaging (MRI) images are used to diagnose breast cancer (BC) and analyze the application effect of epidermal factor receptor-targeted therapy in the treatment of BC. A total of 858 patients diagnosed with BC in Jincheng People’s Hospital from 2019 to 2021 are included and randomly divided into an experimental group and a control group. The experimental group is treated with epidermal growth factor receptor- (EGFR-) targeted therapy, and the control group is treated with conventional chemotherapy according to subsequent treatment modalities. Experimental results show that compared with manual segmentation, machine automatic segmentation includes the local and edge information of the image with higher accuracy, compared with benign and malignant tumors. There are significant differences in the changes of Tpeak, SSmax, El, E 2 , and E 5 , P < 0.05 , with SSmax and El having the greatest changes. After chemotherapy, the recorded maximum diameter of cancer foci in the control and the experimental groups are 26.4 ± 11.6  mm and 20.3 ± 13.5  mm, respectively, and the difference is statistically meaningful ( P < 0.05 ). The ADC value ( 12.74 ± 2.08 ) in the experimental group is higher than that ( 9.7 ± 1.88 ) in the control group ( P < 0.05 ). There is a significant difference in SSmax between the control group and experimental group ( P < 0.05 ), the SImax, pH values of the control group are significantly higher than those of the experimental group ( P < 0.05 ), and the SSmaxR value ( 7.82 ± 6.24 ) in the experimental group is lower than that in the control group ( 10.08 ± 6.25 ), but the difference is not significant, P > 0.05 . The proposed MRI method has high sensitivity and accuracy in the diagnosis of BC, improving the detection rate of lesions, compared with conventional chemotherapy. In addition, epidermal factor receptor-targeted therapy has a better therapeutic effect, with significant changes in cancer foci, which has the value of clinical promotion.