Abstract: The photosynthesis-light response curves of limestone plants Alchornea trewioides,Bauhinia championii,Pteroceltis tatarinowii,Sapium rotundifoliumi in Guilin karst area were fitted with rectangular hyperbolic and non-rectangular hyperbolic models.The results showed that the values of apparent quantum yield(α),the maximal net photosynthetic rate(P_max),dark respiration rate(R_d),light compensation point(L_cp),and light saturation point(L_sp) of the four tree species were higher when fitted with rectangular hyperbolic model than with non-rectangular hyperbolic model.The values and light curves which fitted by rectangular hyperbolic model could not reflect the actual situation,while non-rectangular hyperbolic model were more reasonable because its fitted results better matched physiological meanings.A.trewioides and B.championii had higher apparent quantum yields and lower light compensation,their light use efficiency was higher and shade tolerance was better than S.rotundifolium and P.tatarinowii.