In this work, the interphase interaction mechanism of gas-liquid two-phase flow patterns was experimentally studied in a small gathering and transportation loop using air and oil as working fluids. Bubble flow, slug flow, annular flow, and severe slugging flow was observed and liquid holdup corresponding to each flow pattern was obtained. Based on the multi-resolution analysis method, the time series of the liquid holdup signal was decomposed into 8, 12 and 16 scales using the db4 wavelet, and the dimensionless energy of the detailed components of the liquid holdup signal for each flow pattern was calculated, with a purpose to reveal the multi-scale energy distribution mechanism of the flow pattern. It was found that the energy distribution of bubbly flow exhibits a bimodal structure, while the energy distribution of annular flow, slug flow, and severe slugging flow show a unimodal structure. The energy of bubbly flow is mainly reflected in the shear between liquid bulks and discrete bubbles, as well as the interface effects such as collision, and break up of gas bubbles. The scale corresponding to the main peak of energy distribution curve is relatively constant and does not vary with the maximum decomposition scale.