The mixed stand of Larix principis-rupprechtii and Picea meyeri is one of the dominate forest types in the mountain area of northern China. Many forest scientists believe that the climax vegetation community in the area was pure Picea meyeri stand, however, the existing mixed stands of the two species with larger proportion and long history must have interior mechanism of tree physiology and ecology. To study different growth responses of Larix principis-rupprechtii and Picea meyeri seedlings to light intensity, water availability and nitrogen concentrations under controlled conditions，the experiment was designed using mixed substrates (fine sands∶nursery soil∶cinnamon soil=1∶3∶5) with treatments of four light intensity levels (100%, 45%, 25% and 5%), three soil water capacity levels (100%, 70% and 40%) and four nitrogen levels (20mmol/L, 15mmol/L, 10mmol/L and 5mmol/L). The seedling root collar diameters, height and biomass components of the two species were measured at the end of the experiment. The differences between their growth responses to light intensity, water availability and nitrogen concentrations were analyzed. The results showed that the seedling growth of Larix principis-rupprechtii significantly responded to different light intensities, in which the largest root collar diameter achieved under shade condition and the largest underground biomass achieved under full light (100%). It was also found that no significant responses of Larix principis-rupprechtii seedlings to water availability and nitrogen concentration treatments. It was concluded that the seedlings of Larix principis-rupprechtii required certain shade environment for their healthy growth, although the species is intolerant to shade condition in general. Comparing with Larix principis-rupprechtii, the seedlings of Picea meyeri grew slower and were not sensitive to light intensity treatment, but responded significantly to water availability in which the root collar diameter, aboveground, underground and total biomass were all the largest in the treatment of 40% soil water capacity level. The seedling height of Picea meyeri is highest with low nitrogen level (5mmol/L). It was concluded that wet and high nitrogen conditions would not be beneficial to Picea meyeri seedlings, but low soil water contents and low soil nitrogen concentration would promote the seedling growth. The study showed different growth responses of Larix principis-rupprechtii and Picea meyeri to the conditions of light intensity, water availability and nitrogen concentrations at the seedling stage. Such differences may impact the interspecies relationship, niche differentiation and co-existence of these two species, and ultimately affect the dynamic succession of the forest community.