The flow characteristic of the falling liquid film in the scrubbing-cooling tube was researched in this paper. The ultrasound Doppler velocimetry was adopted to measure the velocity and thickness distribution of the liquid film non-instrusively at different circumferential and axial position. The Reynolds number ranged from 1.0*10~4 to 3.1*10~4. The results showed that both the velocity and thickness of the liquid film were the largest at the 0° position, leading to unevener thickness distribution and the separation of the local liquid film and the sharp increase of the liquid film thickness at the 8° and 16° positions. In the axial direction, because of the effect of gravity, the liquid film velocity increased with the increase of flow distance when the Reynolds numbers was less than 2.0*10~4, whereas, it decreased at large Reynolds numbers since that the resistance became a dominant factor. Both of the thickness and velocity of global liquid film increased with increasing Reynolds number. Furthermore, the increase of the Reynolds numbers made the liquid film more unstable.