With the increase of transformer DC bias events and diversity of the origin, management and control of transformer DC bias has become an important problem to be solved by power enterprise. Therefore, the global control and optimization algorithm based on NSGA-III is proposed, which takes multiple functions as the optimization objective with considering kinds of causes. Firstly, the optimization method model of transformer DC bias control is established. And then, the key steps of NSGA-III algorithm are introduced. Finally, a standard example is used to verify the result. The result shows the validity of the optimization method.