When the development of low permeability reservoir reaches the high water-cut stage，infill well or well spacing adjustment is needed to exploit the remaining oil and enhance the oil recovery efficiency. The technical limited well spacing is an important factor of tapping the potential of the remaining oil. Based on the feature of start-up pressure gradient in the low permeability reservoir and the theory of the oil-water two-phase flow，concepts of pseudo-viscosity and pseudo-potential were introduced. A calculation formula of the technical limited well spacing in the low permeability reservoir was es? tablished based on the potential superposition principle. The influencing factors such as the reservoir permeability，water saturation and the inject-production pressure difference were analyzed with the actual reservoir parameters. The results show that the technical limited well spacing increases with the reservoir permeability，water saturation and the inject-production pressure difference. The calculation results were applied into the actual well pattern arrangement. The maximum well spacing is about 350 m in the areas with better physical properties and low remaining oil saturation and the minimum one is about 250 m in the areas with poor physical properties and high remaining oil saturation. Adjusted well pattern has stronger control ability on remaining recoverable reserves and the oil recovery efficiency will be enhanced by 4.1 percent.