There are provided a network identity authentication method, a network identity authentication system, a user agent device used in the network identity authentication method and the network identity authentication system, and a computer-readable storage medium. The network identity authentication method includes: acquiring, by a user agent, identity information and a registration rule of a target website via a network terminal; acquiring registration information for the target website based on the identity information or generating registration information for the target website according to the registration rule; transmitting the identity information and the registration information to a server agent and sending, by the server agent based on the identity information and the registration information, an authentication request to a website server to complete an authentication process.