Abstract: During drilling through the mid-soft strata with the wire-line core diamond bits, we took following measures; preventing the diamond from carbonizing, polishing and repairing the holes, adopting the starting procedures and so on, to prolong the life of bits and improve the pure efficiency of drilling. While several optimized procedures were separately applied to the drilling at the high, medium and low rotation velocity with the synthetic impregnated bit, nature surface set bit and PDC bit. As having the bit life long enough, we use the "Large Procedure"-the slight wearing down parameters for improving the drilling efficiency at a great rate. So we have got good results.