Embodiments of the present application provide a network access authentication method, apparatus, and system. The network access authentication method mainly comprises: obtaining a user name by a network access management client through encryption using a device ID of a terminal device, and obtaining a dynamic password through encryption using the device ID and a time value within a time step, so that the terminal device performs network access authentication using the user name and the dynamic password. The device ID is uniquely assigned by an authentication server to the terminal device, and thus functions to identify the identity of the terminal device, so that network access authentication can be independent of digital certificates, thereby solving the problem that the terminal device cannot accomplish network access authentication for unsupported use of or unavailability of a digital certificate, while meeting network access security requirements.