To investigate the effect of static magnetic field-assisted freezing (SMAF) on beef quality, quality traits of beef Longissimus dorsi muscle frozen at -18 ℃ and different magnetic field intensities (0, 2, 4, 6, 8 and 10 mT) were comparatively analyzed. The results showed that compared with the control group, SMAF-6, 8, and 10 treatments significantly shortened the phase transition time by 15%, 25%, and 6.7%, respectively (P < 0.05). SMAF treatment effectively improved the water-holding capacity (WHC) of beef (thawing loss, cooking loss and centrifugal loss), and reduced the color difference (ΔE value) (P < 0.05), but had no significant effect on the pH or thiobarbituric acid reactive substance value (P > 0.05). In addition, the results of shear force and myofibrillar fragmentation index (MFI) were consistent, indicating that SMAF treatment maintained the shear force of beef. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed that SMAF treatment could reduce the decrease in protein content of meat after freezing and thawing. In summary, freezing under appropriate static magnetic field intensity (8 mT) can save time, improve the WHC of muscles, reduce the protein loss, and thus improve beef quality.