Abstract: A thermistor thermometer is constructed by mounting a thermistor in one arm of a d.c.Wheatstone bridge.For linearizing the off-balanced thermistor bridge and approching a low nonlinear error the output of the bridge at two ends and middle point of the temperature range is assumed to be linear and then the design parameters of bridge are derived.Calibration shows that the nonlinear errors of bridge's output are small,for example,the errors are smaller than 0.02℃ over a twenty-degree range.This method can be used to design a direct-reading thermistor thermometer or a linear thermistor temperature-frequency transducer.