Abstract: Chlorophill content and net photosynthesis rate were tested in 23 sweet potato varieties and 5 commercial varieties, Taiwan Shu, Chuanshanzi, Xu91-51-1, Jingzha 4 and Xushu 18( as a control). Among the tested varieties, Yunshu 122 had the highest chlorophyll a with 3.19g/L , Yunshu 104 had the highest chlorophyll b with 0.86g/L, Yunshu 112 and Yunshu 122 had the highest total chlorophyll with 4.04g/L and Yunshu 52 had the highest ratio 4.25 of Chl a/ Chl b. Ganxinhongshu had the highest net photosynthesis rate, transpiration rate, stomatal conductivity and intercellular CO2 concentration with 17.98μmol/(m 2?s)、7.64μmol/(m 2?s), 235.63 mmol/ (m 2?s)and320.12μL/L，respectively, and higher than those of Xushu 18.