The purpose of this study is to estimate net primary production of deciduous broad-leaved forest by measuring photosynthesis rate measurement in the natural environment. ”Cryptocarya chinensis” is chosen as study subject in Fu-Shan botanic garden. The net photosynthesis rate is found decreased by canopy degrees. ”Cryptocarya chinensis” is able to sequestrate 3,906 g m^(-2) CO_2 and to transpirate 508 kg m^(-2) H_2O that was measured by net photosynthesis rate and transpiration rate in eleven months. The result has supplied a fundamental parameter for carbon sequestration calculation of broad-leaved forest.