Objective To analyze the diagnostic value of ultrasound and magnetic resonance imaging (MRI) for patients with nonpalpable breast cancer. Methods The clinical data of each 78 patients who were nonpalpable and diagnosed as breast cancer by pathology in our hospital (observation group) and those diagnosed as benign breast tumors (control group) were analyzed retrospectively. The differences in MRI and ultrasound imaging features were compared between the two groups, and the differences in diagnostic accuracy between MRI and ultrasound was recorded. Results There were statistically significant differences in the MRI imaging features of morphology, margin, T1WI signal, T2WI signal and enhancement and the ultrasound imaging features of morphology, boundary, echo, microcalcification, posterior echo attenuation, and resistance index between the two groups (P<0.05). The diagnostic accuracy of MRI in observation group was significantly higher than that of ultrasound (P<0.05). Conclusion Both ultrasound and MRI have important effects in the diagnosis of nonpalpable breast cancer, but the diagnostic accuracy of MRI is higher, and MRI is more favorable in subsequent clinical treatment.