A computer based method for determination of two very important parameters of industrial manufactured thermometers is described in this paper. Some structural influences on thermal response time and immersion depth and the relevant physical principles are discussed and presented. The electrical model of thermal heat flow across the thermo-well and measuring insert of a common industrial thermometer are used to explain and simplify the active complex thermodynamic processes. The measuring system has the possibility to measure, save and analyze the quality of these two main thermometer parameters. Based on self-developed equipment it is possible to make the type test on each new production line, storing the results to production data base and analyzing the data of the large number of measured thermometers or measuring inserts.