Abstract: In order to ascertain the respond of net photosynthetic rate (Pn) of of the leaves of Dryopteris fragrans (L.) Schott to envioromental facters and their functions relation model,the Lci portable photosynthesis system was used to mensurate the Pn, photosynthetically active radiation (PAR), temperature (Ta), vapor pressure deficit (VPD) and CO2 concentration (Cs) of D. fragrans grow in the wild .With the help of the modified model of rectangular hyperbola described by Zi-Piao Ye and the modified stomatal conductance model of Ball-Berry,a couple model is developed and used for describing the response of net photosynthetic rate (Pn) to environmental factors, PAR, Ta, VPD and Cs.It is reified that the model is of high accuracy.The study shows that the net photosynthetic rate throughout the growing season of D. fragrans can be better simulated by the model. Finally, using this coupled model, we studied the reponse pattern of Pn to environmental factors: (1) the response of Pn of D. fragrans to PAR was single-apex curves, with the peak 6.5μmol/(m2?s) (Pn) appearing at 1200μmol/(m2?s) (PAR); (2) the changes of the Pn in response to Ta also followed a single peak curve, with an optimal temperature around 25℃; (3) Pn was showed increased with the increase of Cs, however, it displayed a slowly growth rate when Cs exceeded 450μmol/mol; (4) when VPD was about 4.0kPa, the Pn increased to the top. In conclusion, the presented coupled model describing the reponse of Pn of Dryopteris fragrans to environmental factors provided an effective method for research on the process of photosynthetic physiological ecology of D. fragrans, which is the foundation of further exploration on the best environmental conditions of D. fragrans.The result shows that model can be used to integrate with the environment factors and this can provide the theory basis for the proucton practice of D. fragrans.