Litter decomposition bag burial method is adopted in this study. The collected litters of Pinus koraiensis, Tilia amurensis, and Acer mono were mixed and packed into bags according to their natural proportion. These bags were buried under eleven different microsites, including uprooted trees (UT) with different decayed levels (Ⅱ, Ⅲ, Ⅳ) and their formed pit bottom (PB), mound face (MF) and the controls (forest gap (FG) and intact stand (IS)) in Picea koraiensis-Abies nephrolepis-Pinus koraiensis forest in July 2019. From August to October, three bags of each microsite were collected from each month. After treatment, the mass, C, N and P contents of litters were measured in the labs. Correlation analysis and variance analysis were used to explore their correlations and significance difference between the mass, decomposition rate and nutrient elements of litters at different microsites. The results showed that:(1) microsites and decomposition time had significant effects on the quality of litters(P<0.01). With continuous decomposition, the mass residual rates of litters in each microsite were arranged as follows:PB(85.64%) > MF(83.09%) > FG(81.33%) > IS(80.93%) > UT(80.27%). (2) Their decomposition rates were listed as follows k_IS=k_UT>k_FG>k_MF>k_PB; the Olson index model can simulate the decomposition dynamics of litters in each microsite. The annual decomposition rate k was 0.61-1.42, and the decomposition time required for 50% and 95% was 0.49-1.14 a and 2.10-4.92 a, respectively. (3) The retention rate of C in each microsite showed an overall downward trend, manifested as release mode. The residual rates of N and P in UT and MF microsites continued to decrease, N and P of litters were in the release mode. The change patterns of N and P elements in PB microsites were release-enrichment-release and enrichment-release, respectively. The release was greater than the enrichment, and the final expression was release mode. Microsites had a very significant effect on P release of litters(P<0.01), microsites had a significant effect on N release(P<0.05); the interaction between the microsite and the decay classes of uprooted treefalls had a significant effect on the release of C and N(P<0.01). (4) Retention rate of litter quality and the residual rate of P had a significant or extremely significant positive correlation in all microsites; Retention rate of litter quality and the residual rate of N had a significant or extremely significant positive correlation at level Ⅱ UT, PB microsites, level Ⅲ UT microsites, level Ⅳ UT, PB and MF microsites and FG control; Retention rate of litter quality and the residual rate of C had a significant or extremely significant positive correlation at level Ⅱ UT, PB microsites, Ⅳ PB, MF microsites; retention rate of litter quality and C/N had a significant or extremely significant negative correlation at level Ⅱ UT microsites, Ⅲ UT, MF microsites and FG control. It can be seen that the microsite environment formed by uprooted treefalls has a greater influence on the decomposition and nutrient release of litters than that different decay classes of uprooted treefalls.