The invention discloses a determination method for three-phase transformer bank polarity. The system according to the determination method comprises a tested transformer, a DC power supply, a knife switch and a universal meter. Firstly, the high-voltage side of the tested transformer is divided into three sets of terminals (AB, BC and CA), and the low-voltage side is divided into three sets of terminals (ab, bc and ac); secondly, one set of the three sets of terminals (AB, BC and CA) of the high-voltage side of the tested transformer is connected with the DC power supply; thirdly, one set of the three sets of terminals (ab, bc and ac) of the low-voltage side of the tested transformer is connected with the universal meter; and fourthly, the knife switch is closed, the DC power supply and the tested transformer are instantaneously conducted and then the instantaneous deflection situation of the pointer of the universal meter is observed and recorded. The method is easy to operate, accurate in determination and rapid and safe so that the requirements of large-scale production can be efficiently met.