In this study, non-uniform heating approach in warm T-joint forming process is attempted for the AZ31 magnesium alloy tube. For this purpose, finite element simulation is performed to analyze the appropriate temperature distribution. The validity of the finite element(FE) model of T-joint tube hydroforming(THF) is verified by comparing the FE simulation and experimental results. Using this FE model, appropriate temperature distribution was suggested. In addition, it was showed that the wall thickness could be more uniform by optimizing the temperature condition.