Abstract: Previous studies have noted that parsley extracts had allelopathic effect on Fusarium oxysporium f. sp. Cucumerinum with an inhibitory rate of 12.89%~84.83%. It has also been noted that different fresh parsley root and root soil extracts had different prohibitive allelopathic strengths against cucumber wilt. With steep decline in morbidity, however, the prohibitive allelopathic strengths were within 5.45%~46.95%. Concerns have been reported on the mechanism of parsley extract allelopathy, including protective enzyme systems, soluble substances and active oxygen metabolism of cucumber leaf. However, no concerns have been reported in relation to nitrogen metabolites in cucumber leaf. To study the mechanisms of fresh parsley root and root soil extract allelopathy on F. oxysporium f. sp. Cucumerinum, changes in nitrogen metabolites were analyzed in cucumber seedlings treated with extracts once its first leaf was 5 cm wide. In contrast to earlier studies, this study showed that nitrogen metabolites in "Jinchun 4" cucumber leaves treated with fresh parsley root and root soil extracts were significantly changed. The contents of soluble protein, ammonia, Ser, Arg, Pro and amino acids were increased compared to the control, with the highest increases over the acetone control by 10.58%, 18.31%, 6.54%, 3.10%, 9.64% and 3.16%, respectively. However, nitrate, Gly and Met contents dropped, with the greatest declines of 7.52%, 3.41% and 15.55%, respectively. For the different treatments, the most significant effects on nitrogen metabolites were noted by acetone extracts, followed by ethanol extracts and distilled water extracts. Fresh root extracts caused more distinct changes in nitrogen metabolite contents than root soil extracts.