Broad-leaved Pinus koraiensis forest and Pinus koraiensis plantation were used as objects to carry out in-situ culture experiment through litter treatment and simulated nitrogen and phosphorus deposition. Litter treatments were divided into three treatments:no litter (original group), adding litter (double group) and removing litter (removal group). The simulated nitrogen and phosphorus deposition were as follows:Control CK (0 g N m^-2 a^-1, 0 g P m^-2 a^-1), low concentration N and P (5 g N m^-2 a^-1, 5 g P m^-2 a^-1), medium concentration N and P (15 g N m^-2 a^-1, 10g P m^-2 a^-1) and high concentration N and P (30 g N m^-2 a^-1, 20 g P m^-2 a^-1), respectively. The purpose of the experiment was to study the effects of the increase of litter mass, nitrogen and phosphorus deposition and the coupling effect of the two treatments on the decomposition and release of carbon (C) and lignin. The results showed that in the early stage of the experiment (June), the addition of litter inhibited the C release of L layer and promoted the C release of H layer of plantation, while in the later stage of the experiment (October), it promoted the C release of L layer of plantation, but inhibited the C release of H layer. The addition of litter promoted the release of C from L layer of natural forest in the early stage (June), but had an inhibitory effect in the later stage (October). In contrast to the L layer, the addition of litter continued to promote the release of C from the H layer of the natural forest. Low and middle nitrogen and phosphorus deposition significantly promoted C release and lignin degradation in L and H layers of plantation and natural forest, but high concentration of nitrogen and phosphorus could inhibit C release and lignin degradation. There is no interaction between the two treatments.