Abstract: Effects of different physiological races of M.oryzae on photosynthetic pigments and the parameters of chlorophyll fluorescence of rice leaves were studied by inoculation with M.oryzae to the plants at tillering stage.The results suggested that after treated by M.oryzae,the leaves developed disease symptoms,the photosynthetic pigments were decreased,Fv/Fm,Fv/F0,F′v/F′m,ΦPS Ⅱ,ETR,qP,qN and α values of leavesdeclined significantly comparing to the control group.The sensitivity of different ricevarieties to M.oryzaewas different.After R725 being inoculated with ZA5,the leaf cell structure was destroyed,the content of photosynthetic pigments wassignificantly decreased,and leaf blast was serious.The leaf blast of R720 being infected by ZC8 was the worst,Chl a and Car of of leaves were significantly decreased,Fv/F0,ΦPS Ⅱ and other chlorophyll fluorescence parameters were also significantly decreased.R727 infected by ZG1 showed the most serious leaf blast,the photosynthetic pigments were significantly decreased,the chlorophyll fluorescence parameters were also significantly lower than the control,such as Fv/Fm,qP,ΦPS Ⅱ,ETR,qN and α.