Spindle-type core drill is the most popular drill in geological core drilling engineering. This article presents the improvement of the vertical spindle speed detecting method for spindle-type core drill and introduces the development of speed detecting system based on the key technologies of the sensor, counter module and acquisition machine. The counter module design is optimized to improve the accuracy of the speed measurement. The system has been examined by the NGH drilling program in Mohe, which can surely meet the requirement.