The invention discloses a circuit breaker high-voltage lead temperature alarming device and method. The device comprises a thermistor loop, a voltage comparator, a triode and an LED lamp. The method includes that temperature of a high-voltage lead of a circuit breaker is adopted through a surface mount device thermistor, changing of current in a thermistor series loop is measured according to negative temperature characteristics of the thermistor, voltage at two ends of a fixed-value resistor in the thermistor loop is collected, voltage signals are input into the voltage comparator for comparison with given voltage signals to control the voltage comparator to output high-low levels, and an output voltage signal driving gate circuit of the voltage comparator is used to control turning on and off of the LED lamp to realize an alarming function. The whole alarming device is simple in structure, convenient to operate and capable of accurately realizing temperature alarming of the high-voltage lead of the circuit breaker.