The temporary researches on transformer DC magnetic biasing was summarized, and the researching methods and findings of transformer DC magnetic biasing were analyzed. The main reasons and basic theory of transformer DC magnetic biasing were introduced, and the influences of DC magnetic biasing to transformer were analyzed. The research method commonly is, establish corresponding calculate model by actual measure, simulate and calculate. The main restraining measures are limiting and isolating DC current.KeywordTransformer; DC magnetic bias; Transformer neutrals; Restraining measures