In addition to climate, vegetation types, microbial activities and erosion, leaching is also an important factor influencing the distributions of carbon (C) and nitrogen (N) in soils with elevation. In this study, effects of leaching were discussed to explain the distributions of soil C and N in the coniferous forest along an altitudinal gradient (2600 m~3200 m a.s.l.) on Mt. Gongga. The results showed that the spatial distributions of C, N concentrations and C:N in the humified litter horizon (OH horizon) exhibited a similar decreasing trend with elevation. Since the positive correlation among concentrations of C in litters (Clit), C and N in soils in the OH horizon, the production of Clit was the main factor influencing the altitudinal distributions of C and N in the OH horizon. The obvious altitudinal trend was not observed for C, N concentrations and C:N in the mineral horizons (A, B and C horizon). The contents of C and N in the A horizon were lower in the 2781 m site, while the maximums were in this site for the B and C horizon. The contents of C and N in the rainfall were significantly lower than those in the interflow, which showed the influence of leaching on the spatial distributions of C and N. The results noted above indicated that the leaching process had a non-negligible effect on the spatial distributions of C and N in subalpine coniferous forest soils in southwest China.