The invention relates to a password authentication system and a password authentication method. The system comprises an account login device and an authentication server, wherein the account login device is connected with the authentication server; the account login device is used by a user to input account information and combined passwords of the user when logging in an account, wherein the combined passwords are combined passwords composed of permanent passwords and check passwords; and the authentication server is used for associatively storing preset account information of the user, the permanent passwords and the check passwords, and verifying the account information and the combined passwords of the user input by the use according to the preset account information, the permanent passwords and the check passwords stored in the authentication server. By adoption of the password authentication scheme provided by the embodiment of the invention, the double-password verification mechanism of the permanent passwords and the check passwords is adopted to ensure the password input security so as to guarantee the security of the account.