<p>This work investigated the dynamic behavior of vertical pipes conveying gas-liquid two-phase flow when subjected to external excitations at both ends. Even with minimal excitation amplitude, resonance can occur when the excitation frequency aligns with the natural frequency of the pipe, significantly increasing the degree of operational risk. The governing equation of motion based on the Euler-Bernoulli beam is derived for the relative deflection with stationary simply supported ends, with the effects of the external excitations represented by source terms distributed along the pipe length. The fourth-order partial differential equation is solved via the generalized integral transform technique (GITT), with the solution successfully verified via comparison with results in the literature. A comprehensive analysis of the vibration phenomena and changes in the motion state of the pipe is conducted for three classes of external excitation conditions: same frequency and amplitude (SFSA), same frequency but different amplitudes (SFDA), and different frequencies and amplitudes (DFDA). The numerical results show that with increasing gas volume fraction, the position corresponding to the maximum vibration displacement shifts upward. Compared with conditions without external excitation, the vibration displacement of the pipe conveying two-phase flow under external excitation increases significantly. The frequency of external excitation has a significant effect on the dynamic behavior of a pipe conveying two-phase flow.</p>