The present disclosure provides a combinational circuit and a control circuit. The combinational circuit is applied to an LED drive circuit and includes a detection module and a drive and logic conversion module connected with the detection module. The detection module is configured to detect a state of an external switch, generate a detection signal according to the state of the external switch as detected, and send the detection signal to the drive and logic conversion module; and the drive and logic conversion module is configured to receive the detection signal from the detection module, generate a driving signal according to the detection signal, and drive an operation state of a discharge module for discharging an output electrolytic capacitor of the LED drive circuit by using a state of the driving signal.