From a literature survey, it has been noticed a lack of objective methods to identify and distinct between the intermittent flow sub-regimes. Thus, the aim of this study is to analyze pressure drop fluctuations using statistical methods in order to propose simple tools to characterize the sub-regimes of the intermittent flow. The pressure drop time series were collected from experiments carried out using air-water mixture and 30 mm ID pipe. The utilization of transparent pipes allowed to identify three sub-regimes which are Plug flow, Less Aerated Slug flow (LAS flow), and Highly Aerated Slug flow (HAS flow). It was found that the PDF displayed a unimodal distribution in all cases studied. Meanwhile, the representation of the base width and maximum values of PDF as function of the gas-to-liquid superficial velocities ratio and the mixture Froude number, respectively, showed that the points for each sub-regime are clustered in the same zone. So, these two feature spaces can be used to identify the sub-regimes. A third feature space, based on the statistical parameters standard deviation and kurtosis, was also proposed as a tool to distinguish between the three sub-regimes.