Abstract: Abstract: Shajiang black soil is a typical middle and low production soil in Huang-Huai-Hai Plain. Crop production has been seriously restricted due to the high clay contents and low available water capacity of Shajiang black soil, this paper studied the effects of different modified materials on soil water holding capacity and wheat physiology of anti-drought stress by wheat pot experiment carried out in March 2018, in order to provide technical supports for farmland water managements. According to local field fertilization and water management modes, 4 treatments were designed in wheat pot experiment: chemical NPK fertilizer (CK), chemical NPK fertilizer with maize straw returning (SR), chemical NPK fertilizer with maize straw carbon (SC), and chemical NPK fertilizer with fly ash (FA). Referring to conventional amount of applying fertilizer in northern farmland in Anhui province, the application amounts of chemical fertilizer were 225 kg/hm2 (N), 120 kg/hm2 (P2O5), and 60 kg/hm2 (K2O), respectively, and the application amounts of fly ash, maize straw carbon, and maize straw returning to field were 45×103 kg/hm2, 45×103 kg/hm2 and 6×103 kg/hm2, respectively. As for wheat pot experiment, in each pot, about 10 wheat seeds were transplanted into 30 kg soil after accelerating seeds germination. Soil relative water content was maintained at 80% field capacity until heading stage. When wheats grew up to the heading stage, irrigation stopped and then a drought stress experiment was carried out for 10 days. Wheat leaves collected regularly were stored at -80 ℃ so as to determine wheat physiological and biochemical index. The results showed that both SC and SR improved soil water holding capacity, but both was not significantly different. Owing to the abundance of large amount of hydrophobic crystal minerals like the crystallographic silicon dioxide in the surface of fly ashes, FA had a fast decrease in relative soil water content. The delayed water content of FA was significantly lower than the other treatments, while the available water content was significantly improved. What's more, different modification materials all had the tendency to increase saturated water content and alleviate the impairments of wheat leaves caused by drought stress. Under mild drought stress, the saturated water content of wheat leaves was higher than that of the control group, but no significant difference was found in the contents of proline (PRO), malondialdehyde (MDA), hydrogen peroxide (H2O2) and peroxide scavenging coenzyme in the wheats among the four treatments. However, under extreme drought stress, not only was FA significantly lower than the other treatments in wheat leaves saturated water content, but also FA treatments accumulated more harmful substances like MDA and H2O2 in wheats, which could lead to irreversible damages to wheat physiological conditions. In conclusion, the relative water content of Shajiang black soil was suggested to keep above 38% (SR), 36.5% (SC) and 24.5% (FA), respectively. The plant physiology would get irreversible damage if relative soil water content was under 30.78% (SC), 28.43% (SR) and 22.5% (FA), respectively. Because straws have better performance in holding water by significantly improving the content of soil capillary pore, and fly ashes can do better in providing more available water for soil in spite of holding water poorly, combined application of straws and fly ashes will be conducive to the improvement of Shajiang black soil. Relevant mechanism need to be furtherly studied.