Hepatic steatosis (HS) is one of the common liver pathological changes and is associated with various chronic diffuse liver diseases. Early HS is reversible with timely intervention, thus early diagnosis and precise quantification of HS is of great clinical significance. Liver biopsy is currently the reference standard for the diagnosis and grading of HS, but it is invasive and prone to sampling variability. Recently, magnetic resonance (MR) techniques have been increasingly applied to HS quantification and could possibly be a noninvasive alternative to liver biopsy, among which, proton density fat fraction (PDFF) is considered as the most accurate, reproducible and repeatable imaging biomarker for noninvasive assessment of HS and has shown great potential to monitor the changes in steatosis in longitudinal clinical trials. In this paper, we will review the methods and clinical applications of MR in quantification of HS.