The foundation pit excavation in urban city construction will form a sevious threat to the nearby existing pipeline. Present analytical methods based on FEM numerical simulation and classical elastic foundation beams theories can hardly consider the pipeline-soil separation phenomenon results from the differences of stiffness and deformation between pipeline and soil mass, which will lead to an unsafety prediction of pipeline displacement induced by foundation pit excavation. Based on Pasternak model of elastic foundation beams, an analytical solution of pipeline deformation induced by adjoining foundation pit excavation considering pipeline-soil separation is proposed. Parameter analysis indicates that the maximum displacement of pipeline increases with increase of the length of pipeline-soil separation portion. Moreover, vertical shear stiffness of the soil mass has a significant influence on pipeline deformation when the flexural rigidity of pipeline is small. The analytical model is validated by comparison among analytical calculation results.