The invention discloses a network user identification authentication system, including the client computer, the dynamic password generator and the server, in which the said computer connects to the server through communication network, and the said dynamic password generator connects to the computer, and the said server has the dynamic password checking module. The invention also discloses a network user identification authentication method, including: firstly, the user registers, and then, the client processes login application, and the dynamic password generator generates dynamic password, and then the computer transmits the user identification and dynamic password to the server though communication network, and then, the dynamic password checking module of the server checks the dynamic password, thereby determining the legality of the login application. The authentication architecture of the system in the invention is simple and easy to operate, and it can make users easily login whether or not knowing the network operation, and greatly improve the system's security performance.