A protection circuit for a brushless DC motor, applied to a control device for the brushless DC motor, the protection circuit comprising: a sampling signal input end, configured to receive a current signal of the brushless DC motor; a first resistor having an end connected to the sampling signal input end; a first capacitor having an end connected to the other end of the first resistor, the other end of the first capacitor being grounded; a comparator having a non-inverting input end connected to the other end of the first resistor, an inverting input end of the comparator is used for receiving a reference voltage; a switching element having a control end connected to an output end of the comparator, the switching element is turned on in a case that the control end receives a high-level signal; a fault signal output end, configured to connect a fault signal input end of a main control chip of the control device, wherein the main control chip is a chip for driving the brushless DC motor; and a second capacitor having an end connected to the fault signal output end, the other end of the second capacitor being grounded, wherein a signal input end of the switching element is connected to the fault signal output end, and a signal output end is grounded; the protection circuit characterized in that a total time of T1, T2, T3, and T5 is less than the time in a case that a power module of the control device withstand a large current caused by short circuit, and the level of the fault signal output end is pulled down within this time range; a total time of T1, T2, T4, and T6 meets heat dissipation requirements of the power module, wherein a filter charging time of the first resistor and the first capacitor is T1, a response and delay time of the comparator is T2, a on-time of the switching element is T3, a off-time of the switching element is T4, the discharging time of the second capacitor is T5, and a charging time of the second capacitor is T6. a sampling signal input end, configured to receive a current signal of the brushless DC motor; a first resistor having an end connected to the sampling signal input end; a first capacitor having an end connected to the other end of the first resistor, the other end of the first capacitor being grounded; a comparator having a non-inverting input end connected to the other end of the first resistor, an inverting input end of the comparator is used for receiving a reference voltage; a switching element having a control end connected to an output end of the comparator, the switching element is turned on in a case that the control end receives a high-level signal; a fault signal output end, configured to connect a fault signal input end of a main control chip of the control device, wherein the main control chip is a chip for driving the brushless DC motor; and a second capacitor having an end connected to the fault signal output end, the other end of the second capacitor being grounded, wherein a signal input end of the switching element is connected to the fault signal output end, and a signal output end is grounded; the protection circuit characterized in that a total time of T1, T2, T3, and T5 is less than the time in a case that a power module of the control device withstand a large current caused by short circuit, and the level of the fault signal output end is pulled down within this time range; a total time of T1, T2, T4, and T6 meets heat dissipation requirements of the power module, wherein a filter charging time of the first resistor and the first capacitor is T1, a response and delay time of the comparator is T2, a on-time of the switching element is T3, a off-time of the switching element is T4, the discharging time of the second capacitor is T5, and a charging time of the second capacitor is T6.