A firmware burning method applied in a target device, which includes a storage unit, a target circuit, and a peripheral controller, connected to the storage circuit via a first communication link, is provided. The method include steps of: providing a test fixture having a first node, a second node, and a switch circuit connected across the first and second nodes, the first and second nodes being respectively coupled to the storage circuit and the target circuit; determining whether firmware of the target circuit satisfies a condition; if not, providing a second communication link between the target circuit and the storage circuit via the first and second nodes by turning on the switch circuit, and switching the peripheral controller to a disabled state; and updating the firmware of the target circuit according to to-be-burned firmware stored in the storage circuit via the second communication link.