Exploration for deep mineral deposits is underway in China and great progress has been made， and the same is true for other countries. In drilling deep boreholes， drilling technology and operation are very important， since it directly influences technical and economical indexes of drilling. At present they are guided mainly by data shown at surface devices. However， the data are different from borehole bottom real parameters， and the greater the depth，the bigger the difference. According to the results from Russian super deep borehole drilling research， the difference between them can be up to 25% to 30%. Russian specialists have successfully developed the downhole measurement system with good results obtained. This paper summarizes， discusses， analyzes and introduces the sensors-the key elements in the measurement system， so as to provide some reference for drilling ultra-deep geological boreholes with depth of 13000m in China.