In order to ensure the takeoff safety of an aeroengine， the takeoff afterburner locking function is designed for the afterburner control system. In case of engine backup alarm during afterburner takeoff， the control system shall maintain the afterburner thrust of the engine to ensure takeoff safety. This paper makes a detailed theoretical analysis on the abnormal fault of the afterburner locking and cutting of an engine. Through mechanism analysis， the fault cause judgment method and disposal method are accurately given， and the corresponding troubleshooting measures and safeguard suggestions are proposed. The content is complete， the logic is clear， the point of view is clear， and the conclusion is reasonable， which has high reference value.