Relatively regular areal well pattern has been applied in most oilfields nowadays. But under the influence of reservoir heterogeneity，the development effect of different oilfields varies a lot. To solve this problem，a method of artificial fracturing for oil wells in low permeability zone was proposed，which aims to achieve the purpose of equilibrium displacement in well patterns. Targeting on the rectangular five-spot well pattern，the calculation formulas of water breakthrough time in the fractured oil well and the non-fractured oil well were derived. Besides，aiming at the target that the injected water reaches to different oil wells at the same time，a calculation method of the optimal fracture half-length of the fractured well in the low permeability zone of heterogeneous reservoir was established on the basis of stream line integral method and equivalent well diameter method. The influence of the permeability ratio，well spacing，the difference betwecn two injection-production pressure differences and the fracture conductivity on the optimal fracture half-length was analyzed. The optimal fracture half-length decreases with the difference between two injection-production pressure differences and fracture conductivity. However，when the permeability ratio and the well spacing are large，the required optimal fracture half-length will be relatively long.