Abstract:Parabola, rectangular hyperbola, non-rectangular hyperbola, modified rectangular hyperbola and a subsection function were adopted to model the light-response curve for three different types of vegetations in the dry-hot river valley of Jinsha River, and a method was built to confirm the weak light region which related to apparent quantum yield of photosynthesis. Three main conclusions were gotten: (1)In five simulation methods, only subsection function and modified rectangular hyperbola had good simulation effect for three different types of light response curves; (2)The parameters Pmax,LCP, and Rd from rectangular hyperbola and non-rectangular hyperbola were near to the observations, but the estimates of LSP were always far lower than the observations, modified rectangular hyperbola was adapted to model the curves with phenomenon of light restrain and the estimation of photosynthetic parameters, but this method could not get the photosynthetic parameters for up-raising curve, the parameters estimated by subsection function for different types of curves were all near to the observations; (3) It was relatively theoretical to view the light range divided by the descending point of light-using efficiency on light response curve as the weak light range, the apparent quantum yield of photosynthesis was often lowly estimated when the weak light region could not be confirmed.