This research was conducted to detect corosolic acid, in vitro antioxidant and antidiabetic effect of Prunus padus leaf, also called Bird cherry and is a member of Rosaceae. It is a medium-sized tree with obovate, fine serrated leaves and white flowers. According to the HPLC Chromatogram of standard corosolic acid, leaf samples of Prunus padus displayed a peak with a retention time of 9.855 min. Quantitative analysis revealed a good concentration of corosolic acid i.e 8.032 μg/20 mg d w. In vitro studies showed potent antidiabetic and antioxidant activities DPPH radical scavenging test of Prunus padus showed 91.90 per cent inhibition and standard ascorbic acid showed 82.39 per cent inhibition at 250 μg/ml concentration. Acarbose and Prunus padus both have IC50 values of 193.62 ± 0.634 μg/ ml and 114.72 ± 1.038 μg/ ml, accordingly, as determined by an alpha amylase inhibition experiment. The results demonstrate that Prunus padus possesses a good amount of corosolic acid and can be considered a natural source, which is very influential in neutralizing the reactive oxygen species and damage caused by diabetes and has strong antioxidant and antidiabetic effects.