Abstract: A T-pipe junction, especially the one with an upstream elbow, is one of typical geometries to study the mixing phenomenon of hot and cold flows and the temperature fluctuation caused by mixing flow. Based on three different turbulence models (RNG k-ε, SSG Reynolds stress, LES), the mixing phenomenon in a T-pipe junction with a upstream elbow was simulated. And then, numerical results were compared with the experimental data. The results show that the RNG k-ε model and SSG Reynolds stress model can well predict the experimental data in the non-mixed region such as the upstream elbow, while the simulation results with LES model characterize the actual flows in the mixed zone better.