Abstract: The two-step linearization method for the nonlinear problem is introduced based on the thermistance bridge thermometer, and the analytical expression of linear equation, maximum nonlinear error and maximum error of temperature measurement for several typical plan of which are deduced. The optimal plan of which is also given and the step used to determine the bridge parameters of several typical plan of which is introduced. Both the theoretical analysis and experimental result show that the two-step linearization method is correct. The optimal plan of which is less than about 1.4℃ of the method of one-step linearization for the temperature range from 25℃ to 85℃.

Key words: thermistance, bridge, thermometer, two-step linearization method, maximum error of temperature measurement