Abstract: The study aims to reveal the photosynthetic light response characteristics of sweet potato, and select the best photosynthetic response curve fitting model, accurately calculate the main parameters of photosynthetic. Rectangular hyperbolic model, non-rectangular hyperbolic model, exponential function model and modified rectangular hyperbolic model were adopted to fit the photosynthesis light response curves of three sweet-potato varieties (fresh sweet potato, starched sweet potato and purple sweet potato). The maximum net photosynthetic rate (Pnmax) and dark respiration rate (Rd) fitted by rectangular hyperbolic model were more than the measured values, light saturation point (Isat) was less than the measured values. The Pnmax was much more than the measured values fitted by non- rectangular hyperbolic model, but Isat was much smaller than the measured values. However the Isat, Rd and light compensation point (Ic) were fitted by the exponential model much smaller than the measured values. Only photosynthetic parameters values obtained by the modified rectangular hyperbolic model were closest to the measured values, and this model could fit light suppression section of light response curves of sweet potato. By comparing three types of photosynthetic characteristics of sweet potato, the Pnmax and Isat of fresh sweet potato and starched sweet potato were higher than that of purple sweet potato, but Ic and Rd of three sweet potato types had no significant difference. Photosynthetic parameters value is closest to the measured value obtained by modified rectangular hyperbolic model， and this model can be used accurately and efficiently to study photosynthetic characteristics of sweet potato in the future. Fresh sweet potato and starched sweet potato have greater adaptation to light intensity and potential for accumulation of photosynthetic products.