Abstract: There are more elbows and tees at the branch mouth of gas pipeline in the utility tunnel. Considering the characteristic, the stress and deformation of gas pipeline under the effect of multiple factors were simulated and analyzed using the finite element and numerical theory methods with the utility tunnel engineering at the Beidao West Road in Shanghai as an example. And the following research results were obtained. Firstly, the maximum stress of gas pipeline decreases with the increase of its support spacing, increases with the increase of its weld defect length, and increases at first and then decreases with the increase of its bending angle. Secondly, the deformation of gas pipeline increases with decrease of its support spacing and the increase rate is higher. The deformation of gas pipeline also increases with the increase of its weld defect length, but its increasing rate is lower. Finaly, the maximum stress of gas pipeline is more affected by its direction change. The research results can provide an important reference for the design and construction of the branch junction of gas pipeline in utility tunnel.