In order to explore the effect of litter on forest soil nitrogen and the regulation of nitrogen deposition in the subtropical natural broad-leaved forest and artificial coniferous forest, a simulated leaching experiment was conducted for one year, in which four treatments were designed: soil (control), soil with litter addition (3 times litter addition), soil with nitrogen addition (120 mg/kg), and soil with both litter and nitrogen addition (3 times litter addition and N 120 mg/kg), and then soil soluble nitrogen in bulk soil and soil hydrolysis amino acid in different size soil fractions were analyzed. The results showed that compared with control, the addition of broad-leaved forest litter increased soil ammonium nitrogen and free amino acids, but reduced nitrate nitrogen. Nitrogen addition reduced ammonia nitrogen and increased nitrate nitrogen in coniferous forest soil, but increased ammonium nitrogen and free amino acids in broad-leaved forest soil. In the presence of litter, nitrogen addition significantly increased nitrate nitrogen in broad-leaved soil. The proportions of different size soil fractions were found quite different. Nitrogen addition tended to reduce the proportion of the large fractions and increase that of small fractions for coniferous forest soil, which was inverse for broad-leaved forest soils. The addition of coniferous forest litter significantly increased soil hydrolytic amino acid contents in 2 000-250 μm, 20-2 μm and <2 μm soil fractions. Nitrogen addition increased hydrolytic amino acids in bulk soil, 2 000-250 μm and 20-2 μm soil fractions for conifer forest. However, the presence of litter or nitrogen addition, nitrogen addition or litter significantly reduced hydrolyzed amino acids in bulk soil, 250-53 μm, 53-20 μm soil fractions, meanwhile the effects of litter and nitrogen addition on hydrolytic amino acids were primarily inverse for broad-leaved forest soils. In conclusion, the responses of hydrolytic amino acids (as mineralized nitrogen) in different size soil fractions are different to the litter and nitrogen addition, thus, it is a potential indicator to reveal the changes of soluble nitrogen in coniferous and broad-leaved forests.