Tee-junction is a device used in pipes to transfer, mixing of two dissimilar fluids of different parameters or either same type with varying parameters. The design of the tee-pipe affects its function. The present paper introduces a numerical study of two-phase flow mixing in a T-junction pipe. Water liquid streams in the horizontal main pipe of a T-junction while saturated steam is drawn from the other pipe branch (it lies in a vertical plane). That results in water liquid and steam mixing with steam condensation, and the mixture is directed to exit from the main pipe. The computational model is validated first with the experimental data for a single-phase flow. Two junction angles 90o and 45o between the main pipe and branched pipes are utilized for the T-junction. Different mass ratios for water liquid and steam are examined in the main pipe and branched pipes. Also, various turbulence models are utilized to select the best suitable model for predicting such flows. The comparison ensured the superiority of the realizable k-ɛ model for the present two-phase flow mixing. The obtained results reveal that the T-junction pipe with a junction angle of 45o achieves improved operational performance compared to the pipe with the junction angle of 90o. This result shows that the incline of branch pipe could induce more heat transfer on the area of T-junction, which inevitable could condensate more steam from the branch pipe