The utility model discloses and provides a protection circuit of a fuse. The protection circuit of the fuse comprises a first photoelectric element (BT1), a second photoelectric element (BT2), a relay (K1), a diode (D1), a triode (UT1), a capacitor (C), a first resistor (R1), a second resistor (R2) and a third resistor (R3). The protection circuit of the fuse of the utility model is applied to a main loop of a navigation light controller, when a load meets with an abnormal condition, a variable current is generated, the circuit samples the current and compares and amplifies the current with a reference current, and a signal controls the conduction of the triode via a photoelectric coupler to trigger the relay to act, thereby realizing the short circuit protection and the current limiting protection, preventing a fuse wire from being burnt out due to the excessive current, and reducing the size of the navigation light controller. The protection circuit of the fuse of the utility model is small in size, enables the fuse not to be burnt out easily and to be replaced simply, and is very convenient to maintain.