Abstract: At present, the main development method for tight reservoirs is horizontal well with volumetric fracturing. But for reservoirs lack of natural fractures, it is usually difficult to form complex fracture network system, and the desired stimulation objectives can not be achieved. To solve this problem, based on the research of the induced stress field variation during fracturing, a mathematic model was built by the superposition of the induced stresses and in situ stresses. And the method of optimizing the spacing between volumetric fracturing stages was created based on analysis of the inter-fracture stress interference. The research results show that complex fractures can be created by neutralizing the original geostress by the inter-fracture stress interference. In addition, under the same original geostress conditions, with the increase of fracture height and net pressure inside the fractures, the interval space which creates complex fracture network also increases. Field practical calculations verified the feasibility of the optimization method for fracturing stage spacing in horizontal wells, which is of some reference significance to the design of staged volumetric fracturing in horizontal wells in tight reservoirs.