Since the tight sandstone gas reservoir which is widely distributed in China has become increasingly important in oil field with the further development of resource, it is extraordinarily meaningful for the sustainable and healthy development of China’s energy industry to explore its benefit development mode. Though great achievements have made with the wide use of the hydraulic fracturing technology, which serves as an effective process measure to increase the productivity of a single well, in the development of global unconventional oil and gas resources, there have been many technical problems exposed. A critical one is that if the fractured stage length is too long, the oil and gas resources won’t be effectively exploited, and if it is too short, the operation cost and time will be increased apparently. Therefore, it is urgently required to make plans for determining the optimal length of the fractured reservoir based on different geological features of the oil and gas reservoirs. This paper took the tight oil reservoir in Lower Wuerhe formation in study area as the research case, determined 5 fracturing stage length cases combined with the treatment status and pumping injection procedure of M oil field: Case A (40m), Case B(50m), Case C (60m), Case D (70m) and Case E(80m), and realized fully 3D coupled simulation of the hydraulic fractures in H1 well based on the 3D geomechanical modeling and 3D DFN model with considering multiple factors including stress shadow, proppant settlement and migration using the unstructured grid technology to preprocess it to improve the capacity prediction accuracy of numerical simulation. The productivity prediction results showed that the 10-year EUR (Estimated Ultimate Recovery) of a single well ranged from 35,500 tons to 48,200 tons. With the comprehensive production and fracturing operation cost being considered comprehensively, it was recommended that the optimal length of the single fractured reservoir should be 60 meters.