Abstarct: Regarding to great importance of drilling operation in mining activity, prediction of what can be happened in the future is essential. Classification of those rocks surrounding orebodies and prediction of rate of penetration in them can considerably effect on economic and operational conditions of mines. In current research work, to determine the drillability of Gole Goher rocks masses, a comprehensive study has been carried out (i.e. those papers published from 1950 to 2011 were collected) and the most technical parameters affecting on drillability have been identified. Considering the influence of rock mass and intact rocks in drilling operation, predicting the speed of drilling is a complicated task. Hence, a comprehensive and general approach is required to predict the drillability using effective parameters. In this regard, rock mass drillability index was taken into consideration as a suitable method for classification of drillability of rocks located in mine No.1 of Gole Gohar. Afterward, drillability of rocks located in mine No.1 of Gole Gohar was evaluated. Speed of drilling pattern and its average have been determined. The patterns given were sampled to do rock mechanical test. Fabric, Mohess hardness, Schmit hammer hardness, joint spacing, fracture opening, angle of well axis and joint surface were determined and RDi marks have been assigned to each pattern. At the end, possible relationship of study parameters with speed of drilling and RDi has been identified. Obtained results have shown that RDi has a suitable relationship with speed of drilling and hence it was recommended to use in relative works. In the next stage, utilizing the results obtained from mechanical test and field sampling, rocks mass located around the mine was samples baxsed on their drillability. In this regard, rock masses have been classified into 66 zones with their relative RDi mark. Finally, rock masses located in the mine were classified into two classes: slow-intermediate and intermediate. At the end, obtained results of statistical analysis of drilling speed and RDi were used to predict the speed of drilling in various z ones identified in the area.