The effects of the full day light and the different degrees of the shades (43%,70%,97%) on the photosynthetic characters and on the chlorophyll fluorescence parameters of Forsythia suspensa were examined in these observation. The results indicated that the light compensation point (LCP), light saturation point (LSP)and dark respiration rate (DP) of the F. suspensa plant were at a low level, the value of which decreased with the increasing of shade degree. The diurnal variation of net photosynthetic rate (Pn) presented only one peak under both full day light, and all shade conditions, the daily maxmium and average of net photosynthetic rate decreased significantly with increasing of shade degree, and there by efficiency of the solar energy utilization increased.The diurnal variations of transpiration rate and stomata conductance in leaves were smiilar to that of net photosynthetic rate, the values of transpiration rate and stomata conductance also decreased as increasing of the shade degree. The net photosynthetic rate, transpiration rate and stomata conductance under full day light and all shade conditions showed a positive correlation.The content of chlorophyll a+b,chlorophyll a and chlorophyll b in leaves grown under all shades conditions were significant higher than those under full day light, and increased with increasing of shade degrees, mean while the chlorophyll a/b decreased. Fv/Fm and Fv/Fo were significantly higher than those under full day light and increased with increasing of shade degrees under all shade conditions. Results obtained from above showed that the shade tolerant of the stinging nettle plant was contributed by decreasing the light saturation point, light compensation point, dark respiration rate and chlorophyll a/b, through which it increased the efficiency of the solar energy utilization, the content of chlorophyll a+b, chlorophyll a and chlorophyll b, and the value Fv/Fm and Fv/Fo under the shade conditions.