Objective To investigate the application value of functional MRI in the differential diagnosis between breast mucinous carcinoma and phyllodes tumor(≥ 3 cm). Methods 55 cases of breast mucinous adeno-carcinoma and phyllodes tumors(≥ 3 cm)from January 2012 to December 2017 were retrospectively analyzed. MRI features of 20 mucinous carcinomas and 35 phyllodes tumors were analyzed,compared with pathology. Re-sults There were 20 cases of breast mucinous carcinoma in current study,including 14 cases of pure mucinous carcinoma and 6 cases of mixed mucinous carcinoma. There were 35 cases of phyllodes tumors,including 9 be-nign,18 borderline and 8 malignant cases. There was no significant difference in T1WI signal and enhancement mode between breast mucinous carcinoma and phyllodes tumors. There were significant differences in age,long di-ameter,morphology,lobulation,border,ADC value,EER,T2WI signal and TIC curve pattern(P < 0.05). The area under ROC(AUC)of ADC value and EER for breast mucinous adenocarcinoma and phyllodes tumor was 0.7036 and 0.8029,respectively. Conclusions Multi-model functional MRI can effectively distinguish breast mucinous adenocarcinoma from phyllodes tumor(≥ 3 cm),and EER is more accurate than ADC value.