Intermittent feature of slug flow could lead to variations of flow parameters varying with time and position along the pipe, which may influence dynamic behaviors of the piping system a lot. By considering significance of intermittent characteristic for two-phase slug flow, a dynamic model of a cantilevered horizontal piping system conveying gas-liquid two-phase slug flow is established to analyze natural frequency of the piping system. The functions indicated the variations of flow parameter associated with position along the pipe and time are calculated to analyze various forms of integral equations which are caused by the intermittent characteristic of slug flow to obtain the final matrix equation. The results show that intermittent feature of slug flow could have a crucial impact on natural frequency of the piping system especially when both of superficial gas velocity and pipe length are large enough. Flow parameters in gas bubble zone could play a more significant role for these cases. In addition, it is stated that in the process of predicting natural frequency by the correlation utilized in piping system conveying single-phase flow, it is pivotal to select appropriate forms of liquid holdup and liquid velocity. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.