[Objective] To study the decomposition rate of litter leaf and investigate the relationship between litter decomposition rate and their initial quality in order to provide a scientific basis for forest ecosystem material circulation research in Xinglong Mountain of Gansu Province. [Methods] A field litterbag experiment was conducted in Xinglong Mountain from 2013 to 2016. Litter leaf of three main tree species including Picea wilsonii, Populus davidiana and Betula platyphylla was taken as the research object. Samples of litterbags were retrieved at May, August and November in every year. The litter decomposition rate and their initial quality were studyed. The relationship between litter decomposition rate and their initial quality were clarified. [Results] The leaf decomposition rate of P.wilsonii in middle aged forest was 0.16, and the 95% decomposition period was 19.08 a. The leaf decomposition rate of P.wilsonii in pre-mature forest was 0.13, and the 95% decomposition period was 23.70 a. The decomposition rate of litter leaf for P.davidiana and B.platyphylla was 0.11, and the 95% decomposition period was 28.57 a and 27.27 a, respectively. The decomposition rate of litter leaves of P.davidiana and B.platyphylla was significantly lower than that of the needle leaf of P.wilsonii, which was probably due to the home-field advantage of litter decomposition and smaller aperture of decomposition bags. The litter decomposition rate was positively correlated with N content, but negatively correlated with lignin content, C/N value, lignin/N and K conten. Especially, for lignin content, N content and lignin/N values, the correlation coefficients were above 0.7 000. K content, content of lignin, lignin/N, C/P and cellulose content were key indicators affecting the decomposition rate of forest litter in Xinglong Mountain. [Conclusion] Lignin/N is a key quality indicator affecting litter decomposition rate. The higher the initial lignin/N value of litter leaves, the lower the decomposition rate.