Abstract: With the change of load structure and power consumption pattern, the problem of high voltage, low voltage and voltage fluctuation in transformer area is becoming complicated. In order to make full use of the regulating resources on the grid side and achieve precision management, this paper presents a voltage regulation and evaluation method of medium-voltage bus considering the voltage characteristics of the transformer area. Firstly, a set of evaluation index system of the transformer area is established based on the overall voltage characteristics, voltage limit and line loss. The evaluation indexes are unified into the values of efficacy through the method of efficacy coefficient. Secondly, each index is weighted by sequence relation method, and weighted calculation is regarded as the voltage quality estimation of the transformer area. This estimation can quantify the improvement of voltage quality of the transformer area under a certain regulating scheme of medium-voltage bus, so that the operation of regulating resources on the grid side can be guided effectively. Finally, an example is given to verify effectiveness of this method, by which the voltage quality of the transformer area can be improved without any extra devices.