Using the unique altitudinal topography and climate of Yunnan Plateau,we selected the globally distributed plants Scirpus tabernaemontani and Zizania caduciflora in Napahai,a representative plateau wetland in the northwest Yunnan Province. These two plants,along with their growing soil in situ,were moved to the two plateau wetlands ( Lashihai wetland and Dianchi watershed in Kunming) to analyze the impacts of differences in regional climatic conditions associated with altitudinal decline on the chlorophyll fluorescence characteristics of these two plants during their growth cycles. The results showed that,compared with those in Napahai,where they were transplanted from,after moving to the Lashihai wetland and Dianchi Lake,the chlorophyll contents of Scirpus tabernaemontani and Zizania caduciflora during germination increased by 22.54% and 11.17%,respectively,in Lashihai,and 68.77% and 29.2%,respectively,in Dianchi. The chlorophyll fluorescence parameters also increased or decreased with the gradual decrease in altitude,and these values in the Dianchi Lake were about 1.23.0 times higher or lower than those in Lashihai. The decrease in altitude led to an increase in the maximum value of actualphoto-chemical efficiency ( PhiPS Ⅱ_(max) ) and quantum yield based on CO_2 assimilation ( PhiCO_(2max) ),these two values in Scirpus tabernaemontani and Zizania caduciflora increased to 13.96% and 25.42%,and 89.87% and 27.08% respectively in the Lashihai wetland; and to 24.09% and 46.48%,and 114.77% and 84.33% in the Dianchi Lake. The changes in these parameters during the growing and aging stages were the same as those during the germination stage,but the growth rates and the rates of decline in various parameters during the growing stages were obviously higher than those during the germination stage,while the growth rates and rates of decline during the aging stages were lower than those during the germination stage. This indicates that the chlorophyll fluorescence characteristic indices of these two widely distributed species increased along with the decrease in altitude,and it suggests that the decrease in altitude is beneficial for the enhancement of photosynthetic capacity of both species; however,the plant height increase due to photosynthesis was much faster than the growth of stem diameter duo to photosynthesis,and this adverse effect may ultimately lead to the extinction of these two widely distributed species.