The photo-respiration makes organic matter in photosynthesis decrease. Using inhibitor Na2SO3 at a suitable concentration 20 mg/l helps to increase physiological indicators of tomatoes. Leaf surface, chlorophyll concentration, photosynthesis intensity of the experimental formula are more than the coutrol. At the suitable concentration, transpiration intensity on the plants (g/ dm2 /h) is weaker and leaf area ratio (LAR) is smaller for formation organic matter. All net assimilation rate (NAR), crop growth rate (g/day), fruit yield (kg/plant), concentration of dry matter in fruit, concentration of vitamin C (mg/l00 g fruit), at the optimal concentration are higher than the control. At the higher Na2SO3 concentration (40 - 60 mg/l), there is no large difference between experimental plants and the control.