This study was performed to determine the optimal month of harvest between May and July for wild peach (Prunus davidiana) by comparison of functional materials. The general composition, amino acid and vitamin (A, C, and E) content, and antioxidant activity were determined. With respect to the general composition of wild peach according to the month of harvest, wild peach harvested in May (HMP) and July (HJP) contained mostly carbohydrate, the contents of which amounted to 77.37 g/100 g and 77.92 g/100 g, respectively. The total amino acid content of HMP and HJP were 675.29 mg% and 573.25 mg%, respectively. Regarding the vitamin contents, vitamin A (retinol), E (α-tocopherol) and C in HMP were higher than those in HJP. The total polyphenol content of HMP (218.37 mg TAE/g) was higher than that of HJP (71.45 mg TAE/g). The total flavonoid content of HMP (64.95 mg RE/g) was also higher than that of HJP (32.67 mg RE/g). Moreover, the DPPH and ABTS radical scavenging activities (IC50) were higher in HMP (137.18 μg/mL and 157.15 μg/mL) than those in HJP (160.10 μg/mL and 186.01 μg/mL), meaning that the former produces better antioxidant effects. It can be concluded that wild peach harvested in May contained higher functional materials such as vitamins and amino acids and had a higher antioxidant effect, than wild peach harvested in july.