Water-holding capacity (WHC) refers to the ability of meat to retain moisture when force is applied. As an important processing quality, WHC of beef affects the quality of the final products. The quality of different parts of beef have significant differences. Different WHC not only has an important impact on the flavor, tenderness and juiciness of different parts of beef, but also has an important economic significance. It is helpful to take corresponding measures to control the loss of water by clarifying the WHC of different parts of chilled beef during aging time. Thus, in order to investigate the changes of water distribution during postmortem ageing, the chilled M. longissimus lumborum (LL), M. semimembranosus (SM) and M. psoas major (PM) beef aged for 1d, 2d, 3d, 5d and 7d were investigated. From the perspectives of purge loss, low field nuclear magnetic resonance (LF-NMR) characteristics and muscle structure, the changes of WHC, water distribution and microstructure of the three parts of chilled beef were described. The results indicated that the purge loss of three parts of chilled beef was increased significantly during postmortem aging time. And the WHC of PM were significantly higher than that of LL and SM (P<0.05). The area of relaxation peak (A2) in three parts of beef was decreased significantly (P<0.05) and the differences among P2b and P21 were not significant (P>0.05). The loose arrangement of myofiber and the short length of sarcomere resulted in the poor WHC of SM. PM had longer sarcomere and smaller myofiber diameter. The difference of myofiber structure in three parts of beef resulted in different WHC.