The narrow rectangular channel has the advantages of compact structure and high heat transfer coefficient, and has been widely used in nuclear systems. However, the internal flow of the narrow channel will be affected by the non-inertial force when it is used in undulating conditions. Aiming at the visualized parallel narrow channel boiling experiment system, this study applies the EEMD method to the analysis of signals such as outlet pressure of the test section under rolling conditions. We utilize the features that the variance and energy of the empirical mode decomposition component will suddenly change in the low frequency band, and effectively realize the adaptive removal of signal noise and signal reconstruction under different rolling parameters. This paper also introduces the theory of multi-scale entropy to extract features of different time-scale signals obtained by EEMD method. The obtained signal energy moment and multi-scale entropy changes obviously with the gas-liquid distribution of the experimental section, which can be used as the basis for narrow channel flow pattern identification.