Urban tunneling could cause deformation or even damage of underground pipeline. But there is no method in existing specifications to evaluate the damage. In this article, we propose a safety assessment method for the deformation of flexible pipeline joint induced by tunneling based on the popular soil displacement formula, and give a calculation example in details. This method is easily applicable to engineering by taking into consideration the position relation between pipeline and tunnel and the normal curve shape of deformed pipeline, with few parameters required. It is suitable for cases with no sufficient strata and pipeline data or before fine computation when safety estimation is needed. It could also offer reference for the warning value of environmental monitoring around the tunnel.