Abstract: When oil-water two phase mixer flows through T-shaped pipeline, non-uniform flow distribution, and redistribution of phase volume fraction and phase distribution can occur, and this characteristic is more used in separation operations of multi-phase mixture. This paper analyzes the influence of parameters (such as vertical bifurcation number, mixing flow rate at inlet, oil-content at inlet and flow-rate proportioning, etc.) on oil-water separation efficiency in T-shaped pipeline with Euler multiple-phase flow model and mixing κ-ε turbulence model. The calculation results show that increasing the bifurcation number is available for oil-water separation. There is better range for flow rate proportioning. And the lower mixing flow rate and lower oil content at inlet are helpful for the improvement of separation efficiency. These results will be of significance in guiding structure optimization and oil and water separation efficiency.