Well D05 is a geothermal exploration well in Xiong’an New Area with the total depth of 4014.42 m， and two thermal reservoirs were revealed named Wumishan Formation and Gaoyuzhuang Formation. The situation of serious wear and short service life of bit appeared when drilling in the quartz-rich chert dolomite strata in Gaoyuzhuang Formation. Therefore， the exploration of drill bit was made through the analytical study and practice optimization. As a result， a kind of cone bit suitable for ?215.9mm well diameter in quartz-rich chert dolomite strata was explored， and the problem of bit wear and drilling efficiency were balanced. The drilling task of ?215.9mm well diameter in the third spud of Well D05 was completed smoothly by the use of this bit. The successful application provides a reference scheme for bit usage in similar strata， enriches the deep geothermal drilling technology and provides technical support for the development of deep geothermal drilling.