In view of the unbalanced voltage problem of power system caused by electrified railway accessing to public substation,A 36-node test system and a variety of traction transformers were established on the base of PSCAD,the propagation condition of unbalanced voltage caused by electrified railway was analyzed．The voltage unbalance effect on the power system when it connecting traction transformers with balanced or unbalanced load under the condition of alternation commutation phase was researched．The study find thatSthe rational deployment ofStractionSloadScan effectively improve power quality. The result of simulation analysisSprovides theoretical support and engineering application value for transformer selection and load deployment．