Abstract: Experimental study on the cross-flow-induced vibration of 49 tubes in rotated equilateral triangular array was conducted. The tubes were fixed in both ends and supported by three tube support plates. The behavior and characteristic of the tubes under cross flow from double inlets with opposite direction were obtained, as well as that under cross flow from single inlet. Vibration amplitude, frequency and critical fluid elastic instability Reynolds number of one of the tubes subjected to different inlet velocities were analyzed. The results show that fluid-elastic instability occurs in a lower Reynolds number under cross flow from two inlets with opposite direction, compared with the tubes under cross flow in single inlet. The main vibration frequency when the fluid-elastic instability happens is about 104 Hz, which is close to the theoretical natural frequency of the single span with two fixed ends model. The results are beneficial for the validation of the numerical simulation model for flow-induced vibration of tube bundles.