【Objective】In the present study， effects of straw padding culture substrate for fermentation bed adding di-
fferent super absorbent polymer（SAP） on physiological indexes and yield were studied to provide reference for vegetable water-saving substrate culture.【Method】Three types of SAP（SAP1， SAP2 and SAP3） in two different concentrations（0.4% and 0.8%） were added in straw padding culture substrate for fermentation bed to plant tomatoes. Physical and chemical properties of padding substrate in each treatment and growth index，photosynthetic parameters and protective enzyme activity of tomato were measured. 【Result】Compared with control（CK） adding no SAP， when watering amounts were the same， the tomato yield in 0.8% SAP1， 0.8% SAP2 and 0.8% SAP3 treatments increased by 10.0%，14.5% and 26.5% respectively. Adding 0.8% SAP3 had the best yield increasing effect. SAP addition increased photosynthetic rate（Pn） and transpiration rate（Tr） of tomato leaf compared with CK. As the concentration of SAP increased， the effects were strengthened. At flowering period， in 0.8% SAP addition treatment， superoxide dismutase（SOD） and peroxidase（POD） activities in tomato leaf were significantly higher than CK（P<0.05）. At fruiting period， in all SAP treatment groups， SOD activity in tomato leaf declined but POD activity increased. The increasing range of POD activity in high concentration treatment（0.8%） group was more obvious than low concentration treatment（0.4%） group. 【Conclusion】Adding SAP， especially starch-base SAP（SAP3） in straw padding culture substrate for fermentation bed can improve partial physiological indexes of tomato， thus stimulate plant growth and increase the yield. This technique can be promoted and utilized in vegetable planting.