The invention discloses a method for automatic locking and automatic unlocking of a computer system and a computer system. The method can obtain different detection and identification results based on different conditions so as to achieve the functions of automatic locking and automatic unlocking, and comprises the following steps: at first, when a computer system is in an unlocked state, detecting whether a user exists within a preset range, and when the user is beyond the preset range, recording a duration; then, if the duration is longer than the preset time, controlling the computer system into a locked state; when the computer system is in the locked state and the user is detected to exist in the preset range, judging whether the user has a valid authority; and if the user is judged to have the valid authority, controlling the computer system into the unlocked state.