The invention discloses a biphenyl purification method and an application of purified biphenyl obtained by the method. The method comprises the steps of emulsification shearing stirring action, oxidation treatment, extracting centrifugal separation and vacuum dynamic drying. Purified biphenyl serves as an additive of a lithium ion electrolyte. The method comprises the steps that biphenyl is added to an emulsification stirrer based on combining purification experience on a raw material of the existing lithium ion battery electrolyte; high-purity liquid with low intersolubility with biphenyl is added; emulsification shearing is started; a specified amount of oxidizing substance is added to reach a specified requirement; low-speed stirring is performed; low-boiling-point solvent cleaning is performed for some time; standing or centrifugal separation is performed to obtain to-be-treated biphenyl; and biphenyl is loaded into a dynamic vacuum drier to be subjected to further purification operation to reach a specified index. When purified biphenyl obtained by the method serves as the additive for production of the lithium ion battery electrolyte, the electrolyte has a certain advantage in a quality stability aspect, and the use of a biphenyl-containing electrolyte is facilitated.