The pure cypress forest in the central Sichuan hilly area has problems of reduced biodiversity, lowered capacity for water and soil conservation and underground productivity, and land degradation. The stands in this area are inefficient real-estate and candidates for improvement. The cedar pure forest mixed mass, mixed tree species selected for the Cinnamomum septentrionale, which is an indigenous broadleaf species. The plants, litters, and soils in a mixed forest of cypress and Cinnamomum septentrionale forest were used as the research object. The contents of C, N, and P were compared and analyzed. The changes in ecophysiological characteristics after the introduction of the broadleaf trees are discussed. The results showed:(1) C:N of Cupressus funebris leaves was 132.79 in December and decreased to 84.91 in April of the following year, and Cinnamomum septentrionale had an average annual C:N of 52.6. A low C:N reflects rapid growth of the silver wood in the early stages of tree growth. (2) N:P of cypress and Cinnamomum septentrionale leaves were 10.77 and 10.64 respectively, which were obviously below the threshold of N limitation. The growth of both plants was mainly limited by N. (3) The silver wood litter increased and N:C and N:P decreased, while the correlation between soil nutrient elements and corresponding plant leaves and litter increased. The introduction of the broadleaf species was favorable to trigger the forest soil nutrient recycling process.