Abstract: In this paper, the characteristics and diurnal development of photosynthesis and respiration of cimicifuga nanchuanensis in edge-forest, forest-gap and down-forest were studied. In three habitats, the difference in compensation point of light was not significant, But the light saturation points were very different ;The order of photosynthesis peak value was edge-forest>forest- gap>down-forest ;The most important ecological factor affecting the photosynthesis was PAR; The optimal temperature for photosynthesis was rather low. The diurnal development of respiration in the three habitats had little difference ,correspondent to the diurnal change of air temperature.