Abstract: The thermal characteristics changes of perimysium and endomysium collagen of beef muscle after marinated with three kinds of weak organic acids ( lactic acid, acetic acid and citric acid) and NaCl were investigated.Beef semitendinosus muscle was marinated at 4℃ for 24 h in 2% NaCl solution, 1.5% lactic, acetic and citric acid solutions individually and in mixed marinades for the combination of NaCl and three kinds of weak organic acids respectively. The changes of thermal shrinkage temperatures ( To: onset temperature; Tp: peak temperature; Te: end temperature) of perimysium and endomysium collagen for beef muscle during processing were analyzed by differential scanning calorimeter ( DSC) . The results indicated that the perimysium collagen portion contents in meat marinated with three weak organic acids alone were lower than combined with NaCl.The endomysium collagen portion contents from beef muscle were varied in different marinated groups. The thermal stability of endomysial collagen for all marinated beef was enhanced, and the thermal stability of perimysium collagen for some processed group was enhanced.