Abstract: The essentials oils of C.reticulata Blanco at different ripening stage (July, August, September and October) were analyzed by GC-MS.Fifty terpene compounds, including limonene (47.28%～ 58.40%) , γ-terpinene (8.27%～ 13.23%) , β-linalool (3.48%～ 7.86%) , β-myrcene (6.24%～ 7.50%) , α-pinene (5.07%～ 6.05%) , β-pinene (2.30%～ 3.45%) , octanal (2.04%～ 2.48%) and terpinolene (1.40%～ 2.09%) etc., were identified.In vitro antifungal activity of the above Ponkan essential oils and six potential antimicrobial substances (citral, octanal, nonanal, decanal, β-linalool and α-terpineol) in them against P.italicum and P.digitatum were also determined.Results showed that the inhibitory effect Ponkan essential oils at different ripening stage on P.italicum was better than that on P.digitatum.In potential antimicrobial substances, citral and octanal were observed having strongest antifungal activity against P.italicum, in contrast to that of nonanal and octanal against P.digitatum.The MICs of citral and octanal to P.italicum, together with that of nonanal and octanal to P.digitatum, were both 0.50μL/mL.By contrast, the MICs of β-linalool and α-terpineol to P.italicum and P.digitatum were 2.00μL/mL.