Objective To compare the diagnostic value of ultrasonography and magnetic resonance imaging（MRI） in focal nodular hyperplasia of liver(FNH).Methods A total of 158 patients diagnosed as focal nodular hyperplasia of liver by biopsy of liver cells or pathological examination after operation from July 2001 to October 2016 were selected as the subjects，all patients were examined by ultrasound,MRI,and combination of both tests,and the result of pathological examination as the standard,the differential diagnosis and diagnosis of focal nodular hyperplastic lesions of the liver was compared.Results The pathological results confirmed that 158 cases of focal nodular hyperplasia of the liver in this study,27 cases of lesions was≥50 mm,31 cases was≥30 mm but<50 mm,44 cases was≥10 mm but<30 mm,56 cases was<10 mm;The sensitivity,specificity and accuracy of ultrasound in the diagnosis of focal nodular hyperplastic lesions of the liver were 91.04%,91.21%,and 91.14%,respectively,the sensitivity,specificity and accuracy of ultrasound combined with MRI in the diagnosis of focal nodular hyperplastic lesions of the liver were 95.52%,96.70%,and 96.20%,respectively.The accuracy rate of ultrasound and MRI in diagnosis of nodules≥10 mm,the difference was not statistically significant(P＞0.05);However,in the comparison of the diagnostic accuracy of 10 mm nodules,the diagnostic accuracy of MRI was significantly higher than that of ultrasonic diagnosis,and the difference was statistically significant(P<0.05).Conclusion For the diagnosis of focal nodular hyperplasia of the liver,ltrasound can be used for early screening,and combined with magnetic resonance imaging can improve the accuracy of diagnosis and reduce the rate of misdiagnosis and missed diagnosis.Therefore,ultrasound diagnosis has an irreplaceable role in the diagnosis of focal nodular hyperplasia of the liver.