Abstarct: Failures of systems make distortions in different levels and it can be considered as a threat to society. So, users expect that systems be reliable and safe. To achieve this goal, research on reliability of systems in all of industries are essential. In mining operation and industries, transferring systems is one of the most important units of surface mines and failure of a part or all of them can be threatened as reduction in production and mining profitability. As yet, many important researches were done on reliability and availability of engineering systems throughout the world, but these researches in loading and caring operation and equipment aria were baxsed on engineering judgment. To avoid from unpredicted failures and improvements of transferring operation, awareness of machines operating conditions and statistical control of them was considered as a practical approaches. Statistic and probabilistic evaluations are one of the powerful techniques for prediction of failures and making a safe operation of machines. Estimation of probability of failures and safety operation of machines in determined time domain will be possible with using these approaches. So, in this research the transferring fleet of Sarcheshme copper mine, has been considered. This fleet includes loading and caring system and machinery is a subsystems. After this stage, reliability and failure rate of these systems that working parallel, has been calculated. The results show that reliability for loading system after 100 hours from starting 50% reduces and during 200 hours achieves to 0.2. Also reliability for caring system after 120 hours 50% reduces and during 200 hours achieved to 0.15. Then by considering syntax of these systems that working together series and made transferring fleet, reliability of transferring after about 65 hours from start to working achieved to 80% and during 200 hours slowly attend to 0. In the last step of this research after determining reliability of loading and caring systems, scheduling of preventive maintenance for subsystems of drilling machines has been done baxse on keeping reliability of subsystems at 80% and baxsed on this presented maintenance scheduling, reliability of transferring fleet of Sarcheshme copper mine will be improved by 98%. Finally, details of preventive maintenance schedules have been presented for any of subsystems