By adding different litters and tannic acid with different rates to forest soils from Wuyi-Mount under cultivate condition, the effects of secondary metabolism on soil soluble nitrogen was studied. The results showed that soluble nitrogen content decreased by adding litters. Soluble nitrogen decreased by 12.0% - 27.5% for red soil with the addition of fir litter. The effect (p<0.05) of fir litter treatment on soluble nitrogen content was higher than that of bamboo. Compared with control, the treatments with high rate of tannic acid significantly (p<0.001) reduced soluble soil nitrogen of yellow-red soil with a decrease by 40.6% - 48.1%, but the effect of low rate of tannic acid on soil soluble nitrogen was not significant. The results indicated that the effects of litters, particularly fir litter, on soil soluble nitrogen possibly depend on tannic acid, which affects the soil organic and inorganic nitrogen turnover in soil.