The invention relates to a united identity authentication method and system for a power distribution communication wireless private network. The method comprises the following steps of acquiring a network access attachment request initiated by a terminal through a core network of the power distribution communication wireless private network, wherein the network access attachment request contains united identity authentication parameters of the terminal; transmitting an access request to a secondary authentication gateway by the core network after the terminal passes authentication certification; receiving a secondary authentication result of the secondary authentication gateway for the terminal according to the united identity authentication parameters by the core network; transmitting network access success information and carrying information to a base station and the terminal by the core network if the secondary authentication result is passing authentication; transmitting network access failure information to the terminal by the core network if the secondary authentication result is failing in authentication. Secondary authentication is performed when the terminal accesses the network, the safety performance of the power distribution communication wireless private network is effectively improved, and distribution communication wireless private network application requiring high real-time performance can be met.