Abstract: By comparison between technical indexes of every drilling stage in Henan Oil Field, We have seen that footage per bit and average drilling speed increased by 15.19% - 41.12% and 23.54% -55%(compared with preceding drilling stage). Analysed the use.cases of bit in five block of Henan Oil Field and the influence of stratum drillability grade on the selection of bit types. The best plan of selecting bit is concluded for the differential intervals of five geological units in Henan Oil Field. At the same time, above - mentioned results are analysed and proved in theory combined with stratum characteristics. The primary tentative idea of developing drilling technology is put forward at last.