Objective To observe the application values of ultrasound combined with MRI multiple quantitative parameters in the diagnosis of breast cancer. Methods The clinical data of 120 cases of patients diagnosed as breast cancer were retrospectively analyzed, and all patients were given ultrasound and MRI examination. The pathological examination was taken as the "gold standard", and the sensitivity, specificity, accuracy, positive and negative predictive values of ultrasound, MRI and two combined examinations were evaluated in the diagnosis of breast cancer, and the differences of MRI multiple quantitative parameters [apparent diffusion coefficient (ADC), T peak (Tpeak), early enhancement rate (EER), peak enhancement rate (PER)] in benign and malignant breast lesions were observed. Results The values of ADC and Tpeak in the diagnosis of malignant breast lesions were lower than those of benign lesions by MRI while the values of EER and PER were higher than those of benign lesions (P<0.05). There was no significant difference in the sensitivity, specificity, positive predictive value and negative predictive value of ultrasound, MRI and ultrasound combined with MRI in the diagnosis of breast cancer (P>0.05). The diagnostic accuracy of ultrasound combined with MRI was higher than that of ultrasound (P<0.05). Conclusion Ultrasound and MRI can have high sensitivity, specificity and accuracy, and obvious image features. Ultrasound combined with MRI multiple quantitative parameters can help reduce the misdiagnosis rate and missed diagnosis, and enhance the diagnostic accuracy.