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　　The characteristics and formation mechanisms of waterflood-induced fractures formed during the process of water injection development and their influence on development adjustment of low-permeability reservoir are studied. This paper uses the low-permeability sandstone oil reservoir of the sixth member of the Triassic Yanchang Formation in the Wangyao area of the Ordos Basin as an example. A waterflood-induced fracture is a water well-centric open fracture which is formed due to high water injection pressure during the long period of water injection development. Waterflood-induced fractures are tensional fractures with large scale and length. They extend and develop along the main flow fracture direction or in-situ stress direction. With the development of low permeability sandstone oil reservoirs, waterflood-induced fractures have grown continuously and extended from water well to oil well. Because of the high permeability in the fractures, waterflood-induced fractures can cause rapid waterflood and water breakthrough of oil wells, which is the most serious anisotropy of low-permeability sandstone oil reservoirs during the middle and later stages of water injection development. Waterflood-induced fractures have three formation mechanisms. Among them, the main formation mechanism is because water injection pressure is higher and makes natural fractures open and extend. After formation of a waterflood-induced fracture, the flow field and pressure field in low-permeability sandstone reservoir are completely changed, which impacts on the water injection-development effect of the low permeability sandstone reservoir. At the same time, we need to pay attention to a series of deeper problems to development and adjustment of low-permeability sandstone oil reservoir during the mid to high water content stage.