The invention relates to a calibration device and method for a root canal length measurement instrument. The calibration device comprises a measurement signal generating circuit, an on-off control circuit, an analog electronic switching circuit, a calibration load circuit and an external measurement circuit, wherein the measurement signal generating circuit is used for generating a current measurement signal, detecting the voltage signal of the calibration load circuit and generating a calibrated current measurement signal; the on-off control circuit is used for controlling the analog electronic switching circuit to be connected to the calibration load circuit or the external measurement circuit; the analog electronic switching circuit is used for outputting the current measurement signal to the calibration load circuit or outputting the calibrated current measurement signal to the external measurement circuit; the external measurement circuit is used for outputting the calibrated current measurement signal to an external root canal file and lip hook circuit. Compared with the prior art, the calibration device has the advantages that the measuring circuit is small in size, the price is low, the failure rate is low, the power consumption is low, the control is simple, the internal structure of the root canal length measurement instrument is more compact, the whole size is smaller, the cost is lower, the function is more reliable, and the calibration accuracy is high.