Abstract: Based on the calorimetric tritium method, an automatic tritium measurement device was designed. Utilizing several technologies of double-cup butting measurement, symmetrical arrangement of large scale thermocouple and preheating of standard heating resistor, the preheating time is decreased from 15 h to less than 5 h and the uncertainty reaches 0.4% when the thermal power is in the range of 300-3 000 mW. And it can realize quick and high-accuracy measurement of tritium content.