Abstract: To explore the effects of nitrogen, phosphorus and potassium on the physiology of Pyrrosia petiolosa as well as the synthesis and accumulation of chlorogenic acid(CGA), tissue culture seedlings of P. petiolosa were used as materials, and three concentration gradients of low nutrient( no fertilization: N₀, P₀, K₀ ), normal fertilization( N: 0.20 g·kg^-1, P: 0.15 g·kg^-1, K: 0.15 g·kg^-1 )and high nutrient( N₁: 0.40 g·kg^-1, P₁: 0.30 g·kg^-1, K₁: 0.30 g·kg^-1)were set up. Seven treatments were set up to NPK, N₀PK, N₁PK, NP₀K, NP₁K, NPK₀ and NPK₁, and the resistance physiological indexes, CGA contents and key enzyme activities of P. petiolosa under different treatments were determined. The results were as follows:(1)Nitrogen, phosphorus and potassium fertilizers had significant effects on the resistance physiology of P. petiolosa. The activities of superoxide dismutase(SOD)increased significantly under high nitrogen and low potassium treatments, but catalase(CAT)activities rose significantly under low and high treatments of three nutrients.(2)The contents of CGA in P. petiolosa was significantly affected by different nutrient levels of nitrogen, phosphorus, and potassium. The CGA level in normal fertilization was the highest, reaching 12.92 mg·g^-1, while the CGA content in high potassium fertilization was the lowest, 7.79 mg·g^-1. Potassium fertilizer had the most significant effect on CGA content.(3)The key enzyme activities of CGA synthesis were significantly different in different fertilization treatments. The content of CGA was positively correlated with the activities of quinate o-hydroxycinnamoyl transferase(HQT)and 4-coumaroyl coenzyme ligase(4CL), and negatively correlated with the activity of quinic acid shikimate o-hydroxycinnamoyl transferase(HCT). HQT, 4CL and HCT were the key factors leading to the difference of CGA content. The results of this study provide a theoretical reference for the artificial cultivation of P. petiolosa.