Abstract: During the staged fracturing in horizontal wells,in order to form a complex fracture network and improve the post-fracturing performance,a numerical simulation method was used to optimize fracture spacing of "fracture network" in horizontal well.Based on fracture diverting mechanism,homogeneous and isotropic 2D maximum induced stress anisotropy model was built,maximum induced stress equation between fractures was deduced,and the optimal fracture space was worked out.According to field data,The induced stress anisotropy was calculated under Poisson’s ratio of 0.2-0.5 and fracture spacing of 40-90 m.The result showed the lower the Poisson’s ratio,the higher the fracture induced stress difference,the longer the induced stress would propagate,as the distance increased,the induced stress difference first increased and then decreased,when the spacing between two fractures was optimal,the induced stress difference was maximum.The study showed the optimal spacing between fractures could maximize induced stress difference between fractures,facilitating the formation of complex fracture network,and improving the connectivity between oil and gas and wellbore.The study results provided a new approach for fracturing optimization in low permeability oil and gas reservoirs.