Abstract： The effects of broad-leaved tree introduction and litter formation on the productivity and soil microbial properties were investigated in the Chinese fir [Cunminghamia lanceolata (Lamb) Hook] plantation. The results showed that the productivity was increased by 200% after the introduction of N-fixing Alnus cremastogyne compared with that of non-N-fixing Acer mono, and the increment was obtained from A. Cremastogyne. The productivity of fir was not affected by tree species (P<0.05). A. Cremastogyne increased the total organic C by 16.8%, and decreased soil basal respiration and qCO_2 by 13.1% and 16% in 0～10 cm soil, respectively. The microbial biomass C in soil at 0～10 cm depth was increased by 10.8% by litter (P<0.05). Furthermore, the tree species and litter had significant interactive effects on soil basal respiration and qCO_2 (P<0.05). The total organic C in 0～10 cm soil was positively related with the productivity of tree (R~2=0.775, P=0.005, N=12), and the microbial biomass C was significantly related with total organic C (R~2=0.438, P=0.032, N=24). The results suggested that the tree species and litter were both important to soil microbial properties in mixed plantation.