The present invention provides a thermal control system and a thermal control method for an electronic device. The thermal control system comprises: an integrated circuit, a determining unit, an adding unit, and a proportional-integral-derivative (PID) controlling unit. The determining unit is utilized for determining at least a target thermal parameter for the integrated circuit. The adding unit is coupled to the integrated circuit and the determining unit, and utilized for receiving the target thermal parameter and at least an actual thermal parameter of the integrated circuit to generate at least an error thermal parameter accordingly. The PID controlling unit is coupled to the adding unit and the integrated circuit, and utilized for generating at least a performance level for the integrated circuit according to the error thermal parameter.