The changes of tenderness and water holding capacity of different grades Hengshan lamb meat slices from Northern Shaanxi province within 48 h after slaughter were studied. Longissimus muscle(HQ) and abdominal muscle (LQ) were measured at 4, 8, 12, 24 and 48 h after slaughter; the shear force and drip loss of sarcoplasmic and myofibrillar protein, cooking loss rate, solubility, myofibrillar protein degradation of polymerization were measured. With the time increases after slaughter, two kinds of meat shear force increased significantly in 4-8 h (p<0.05), meat drip loss significantly reduced, cooking loss rate and sarcoplasmic protein solubility were both significantly increased (p<0.05); pork myofibrillar protein solubility decreased significantly in 4-12 h but gradually increased after 12 hrs (p<0.05). After slaughter process, HQ meat shear force, drip loss and cooking loss rate were all significantly lower than that of LQ (p<0.05), sarcoplasmic protein solubility was significantly higher than that of LQ group (p<0.05); after 12 h, HQ myofibrillar protein solubility was significantly lower than that of LQ group (p<0.05), but after 20 hrs it was significantly higher than that of LQ (p<0.05). The SDS-PAGE results of two kinds myofibrils were consistent with the change of solubility. Within 2 days after slaughter, Hengshan mutton tenderness tends to be tender, its water holding capacity and stability decreased. For lower quality lamb meat from longissimus muscle, its tenderness and water holding capacity was good, but protein stability was poor.