Abstract: The present paper deals with the declining of Cunninghamia lanceolata (Lamb.) Hook. Based on the analysis of air monitor, chlorophyll, K+ efflux, electric conductivity of leacheate from the leaves, nutrient elements such as N, P, K, Ca, Mg and total sulfur content in the leaves, and tree stem analysis. The result indicates that the chlorophyll, P, K, Ca, Mg of C. lanceolata and its growth yield in the controlled zone were larger than that in the air polluted zone. However K + and electrolyte of the leacheate from the leaves of C. lanceolata effused in greater number through the membrane than that in the controlled zone. The total sulfur and nitrogen content had been accumulated in the leaves of C. lanceolata in Dasheng Mountain.