Abstract: Combined with the concrete geothermal exploration project,using ATmega8 series chip developed a kind of digital thermometric indicator which is suitable for measuring the ground water temperature in a few hundred meters deep drilling holes.It is very convenient to obtain the ground water temperature in drilling holes accurately and continuously,and have resolved the problem of measuring the temperature in shallow depth geothermal exploration.The emphasis of this paper lies in introducing the working principle of this digital thermometric indi-cator and carrying on the analysis to the concrete application situation about it.