Excessive liquid carryover in T-junction due to splitting nature of two-phase flow causes serious issues in piping system. A three-dimensional numerical model is employed to investigate two-phase flow split behavior of slug flow in a circular-section regular T-junction with 0.0752 m diameter. The Volume of Fraction method combined with k-ϵ turbulence model and initial sinusoidal perturbation in ANSYS FLUENT is adopted to characterize the effect of slug flow behavior on the phase separation efficiency. The preliminary result reveals that the simulation work can study slug flow split in great detail and the slug characteristic plays an important role in understanding split behavior. © 2018 The Authors, published by EDP Sciences.