Abstract: In order to explore changes in quality of aged beef, provide certain guidance for the actual production of Liangshan cattle cold fresh meat, the longissimus dorsi of Liangshan cattle were aged for 1, 2, 3, 4, 5, 6 and 7 d at 4 ℃ .The total number of bacteria, stiffness index, volatile base nitrogen value (TVB-N), barbituric acid value (TBARS), water loss rate, texture properties, myofibril fragmentation index (MFI), protein thermal properties and other indicators were measured and analyzed. The results showed that even though the total number of bacteria, TVB-N and TBARS values ​​were increased significantly when acid discharge for 7 days, ​​the Liangshan cattle beef were still within the value range of fresh meat. The hardness, water loss rate, and stiffness index of Liangshan cattle beef after acid discharge for 3~7 days all decreased significantly (P<0.05), and the MFI value increased significantly (P<0.05). At this stage, the muscle skeleton protein was degraded and the beef was tender. The degree was greatly improved, and the water retention was improved. The thermal denaturation temperature of Liangshan cattle myosin was higher after acid discharge for 2 d and 3 d, a large amount of hard-to-dissociate actomyosin was formed in the muscle, and then the denaturation temperature dropped significantly (P<0.05), and the thermal stability of the muscle was reduced. Therefore, from the perspective of improving muscle quality and improving the eating quality of Liangshan cattle, the slaughtered Liangshan cattle has better eating quality after acidification for 4~7 days.