A method and device for realizing a verification code are provided. In some embodiments, a character verification code is obtained and displayed when it is determined to perform identity verification. The character verification code has an incorrect character based on a priori knowledge. The user is prompted to input a correct character corresponding to the incorrect character in the character verification code. Verification information is received. It is determined that the verification is successful when the verification information corresponds to the correct character of the prior knowledge; otherwise, the verification failed.