Abstract: Some species within Dendrobium demonstrated characteristics of crassulacean acid metabolism. Our objective was to establish an effectvie measurement system to clarify the comprehensive linkage among chlorophyll fluorescence, carbon assimilation and stomatal movement of three dendrobia. In the research, three species of dendrobia were selected, including D. chrysotoxum, D. nobile and D. primulinum. Meanwhile, Kalanchoe blossfeldiana was employed as control. By using Li6400 portable photosynthesis system equipped with leaf chamber fluorometer, the electron transport of PSⅡ and rate of carbon assimilation were inspected. Meanwhile, the corresponded stomatal movement and the structure of stomata complex on fresh leaf were observed under scanning electronic microscope and confocal laser scanning microscope. The results showed that CAM plant D. primulinums stoma almost closed under light, but the electron transported in photosynthesis system. The phenomenon of stomatal opening and closing nonuniform was obvious in D. chrysotoxum and D. nobile.The PSⅡ photochemistry of D. chrysotoxum with obvious characteristics of C3 plant had the highest yield of effective quantum. However, the other three materials accumulated dry matter slowly as low photochemical efficiency. Realtime observation on electron transfer, carbon assimilation and stomatal movement of fresh leaf would be the efficient means to research their characteristics of crassulacean acid metabolism.