Abstract: Based on a 30 hm² mixed broadleaved-Korean pine (Pinus koraiensis) forest monitoring plot at Fenglin National Nature Reserve in Xiaoxing’an Mountains, China, we estimated leaf area index (LAI) for major tree species and total LAI for all species using empirical models between LAI and basal area. We explored the influence of four kinds of terrain factors (including altitude, slope degree, slope aspect and curvature) and the combination influence on the spatial distribution of LAI. Results showed that the four terrain factors all had a significant effect on spatial distribution of LAI for five major tree species, including P. koraiensis, Abies nephrolepis, Tilia amurensis, Ulmus laciniata and Acer mono. But the slope aspect had a significant effect on the spatial distribution of LAI for Betula costata. The four kinds of terrain factors all significantly affected the spatial distribution of total LAI for all species. The plot could be divided into five habitat types, including the ridge, sunny, valley sunny side, shady and valley shady side. The habitat types had significant effects on the spatial distribution of total LAI, and the LAI in the ridge with a mean value of 8.85 was significantly higher than that in the other habitat types, followed by LAI in sunny with a mean value of 7.62. The LAI in the valley sunny and shady sides did not differ significantly, and the valley shady side had the lowest LAI, with a mean value of 4.42.