The light and nutrient conditions are important environmental factors that affect plant growth, and plants of different life forms have different responses mechanisms to environmental heterogeneity. The seedlings of the deciduous broad-leaved tree species Quercus acutissima Carruth. and the evergreen broad-leaved tree species Phoebe bournei (Hemsl.) Yang were selected as the research objects, and a total of 8 treatments were formed by setting 2 light gradients (the full light and 45% full light) and 4 fertilization gradients (no fertilization, the nitrogen and phosphorus supply ratio of 5, 15 and 45). In this paper, we study the effects of light, fertilization and their interaction on the biomass and leaf morphology, physiological and chemical properties of the Quercus acutissima and Phoebe bournei, and explore the relationship between leaf functional traits and plant biomass. The results showed that: (1) light, fertilization and their interaction had significant effects on photosynthetic gas exchange parameters (except for water use efficiency), chlorophyll fluorescence parameters, leaf morphology indicators (Un-including specific leaf area), unit mass leaf nitrogen content, and root shoot ratio. In addition, light and fertilization showed significant impacts on above ground biomass and total biomass (P<0.05). (2) The treatment of full light significantly increased the total leaf area, aboveground biomass, underground biomass and total biomass of the Q. acutissima and P. bournei (P<0.05), while the treatment of shading reduced the non-photochemical quenching coefficient, photosynthetic nitrogen-use efficiency and root shoot ratio, but increased the unit mass leaf nitrogen content. (3) In the full light treatment, fertilization significantly promoted the water use efficiency of the Q. acutissima and P. bournei (P<0.05). In the shading treatment, the nitrogen and phosphorus supply ratio of 45 markedly increased the net photosynthetic rate and water use efficiency of the Q. acutissima and P. bournei (P<0.05). (4) The Q. acutissima and P. bournei preferred resource acquisition strategies in the full light condition and preferred resource conservation strategies in shading condition. In the light and fertilization treatments, the total leaf area of the Q. acutissima and P. bournei were significantly positively correlated with aboveground biomass (P<0.05). In short, the total leaf area was a stable indicator for predicting changes in the aboveground biomass of the seedings of Q. acutissima and P. bournei. The fertilization was helpful to increase the ecological adaptability of the seedings of Q. acutissima and P. bournei. in a low light environment.