Abstract A new method to identify flow regime in two-phase flow was presented, based on signal processing of differential pressure using Hilbert Huang transform (HHT). Signals obtained from a Venturi meter were decomposed into different intrinsic mode functions (IMFs) with HHT, then the energy fraction of each intrinsic mode and the mean value of residual function were calculated, from which the rules of flow regime identification were summarized. Experiments were carried out on two-phase flow in the horizontal tubes with 50mm and 40mm inner diameter, while water flowrate was in the range of 1.3m 3·h −1 to 10.5m 3·h −1, oil flowrate was from 4.2m 3·h −1 to 7.0m 3·h −1 and gas flowrate from 0 to 15m 3·h −1. The results show that the proposed rules have high precision for single phase, bubbly, and slug, plug flow regime identification, which are independent of not only properties of two-phase fluid. In addition, the method can meet the need of industrial application because of its simple calculation.