The invention relates to an on-line calibration device and a calibration method for infrared temperature sensing protection in a power high-voltage cabinet, which is characterized in that the device comprises a power high-voltage cabinet, a temperature converter, a control module, a temperature aligner and a protection system of the power high-voltage cabinet. The temperature of the high-voltage equipment in the cabinet is scanned by a miniature infrared temperature measuring probe in the high-voltage cabinet of the electric power, and to a temperature converter, after conversion, it is sent to the control module for comparison with the preset fault value in the control module, If the fault value is slight, the overheat alarm in the protection system of the high voltage cabinet sends out an alarm. If the fault value reaches the malignant overheat tripping value, the control module controls the trip coil of the circuit breaker to trip the switch, thereby controlling the trip of the switch. Under the condition of non-contact temperature sensing, the invention ensures the safety, timely and effective protection for the high-voltage cabinet of the electric power when the overheating fault occurs.