The drilling parameters in the rotary drilling process were sampled and analyzed using online monitoring system. The theoretical expressions between the derived parameters and direct sampling parameters were constructed, and the model of formation work ratio considering multi-factor combinations was also proposed to realize the perfect integration of geological conditions and drilling parameters. With the case study of a construction field of the high voltage substation in Chongqing, the curves of different formations such as backfilled soil, silty clay sandstone and mudstone formations were described and compared with the geological survey, the comparison presented obvious difference of different formations. The above results indicated that rational work ratio thresholds were significant to identify the strata characteristics. And then, the work ratio threshold of different formations was optimized near the surveying piles based on the statistical analysis theory to prove the reliability of the threshold range of different formations according to the geological information. In addition, the threshold value were used to verify the formations far away from the surveying piles, the results deeply calibrated the proposed method and verified the rationality of the threshold values. Therefore, the proposed method to determine the threshold range based on formation work ratio model can be used to another different formations and strata identification.