Abstract Considering influence of fluid parameters, pressure and flow rate ,etc, on the bending motion of pipeline, the 12-equation models described straight and curve pipe conveying fluid were improved,and also were verified by numerical examples. Based on these models, dynamic problems of complex systems were solved by transfer matrix method which is convenient and feasible, and also has more advantages compared with finite element method, etc. In this paper, the influence of steam parameters on the natural characteristics of steam pipeline systems was studied. The results show that the extent of the influence of steam pressure on the natural frequencies of pipeline systems was mainly dependent on the parameters of pipe section, and the influence of flow rate was relatively not significant. These conclusions have some reference value for engineering practice.