Abstarct: The non-functioning of the systems leads to disruption at various levels and is considered as a threat to the society; And users expect the systems to be safe and reliable. Drilling equipment is the most important operating scale in open pit mines, the total or partial failure of which minimizes the production and profitability of the mine. In order to increase the optimal performance of drilling machines and prevent unwanted stoppages in the mine, statistical control and knowledge of the conditions and working methods of the machines is one of the practical solutions. Reliability analysis and evaluation is one of the powerful solutions for the proper functioning of devices at a certain time and predicting breakdowns in devices. By using this method, it is possible to estimate the probability of device operation and failure in a certain period of time. In this research, after presenting the concepts of probability, definitions and reliability modeling in the second chapter, the study of drilling and mining equipment has been introduced. In the fourth chapter of this research, the operational subsystems of the drilling machine and reliability modeling of the hydraulic subsystem, drilling and the drilling machine of Gol-Gharsirjan mine No. 5 and the accessibility of the drilling machine and subsystems have been presented. In the fifth chapter of the research, the preventive maintenance program for the drilling machine and the hydraulic and drilling subsystems has been discussed, with an emphasis on maintaining the performance of the drilling machine and each of the subsystems. The reliability of the drilling rig and subsystems will be improved up to 98% by providing a preventive maintenance program.