Abstract: With LiCor-6400 portable photosynthesis analysis system,light compensation point and saturation light intensity for the pteridophyte Neocheiropteris palmatopedata grown in greenhouse were studied.By controlling light intensity,CO₂ concentration,temperature and humidity in the leaf chamber,carboxylation efficiency and CO₂ compensation point were analyzed and laboratory studies were conducted to investigate the relations between photosynthetic rate and light intensity,temperature and humidity.Compensation irradiance was 5.8 μmol·m^-2·s^-1.Saturation light intensity was about 1000 μmol·m^-2·s^-1.Carboxylation efficiency of leaves was about (0.02665) and CO₂ compensation point was (66.1μmol·mol^-1).The net photosynthetic rate was the highest at leaf temperature 20℃,the optimal temperature was from 17 to 27℃.When humidity went up from 20% to 80%,the rate of net photosynthesis increased.