PT. Semen Padang is the first cement company in Indonesia which was established on March 18, 1910. To produce raw materials into finished materials, PT. Semen Padang uses 3 main types of machines, namely raw mill machine, kiln mill and cement mill. To achieve the production target, PT. Semen padang must have a machine that is qualified in operation. Therefore, proper maintenance of critical machinery in PT. Semen Padang. One of the critical machines that need maintenance is the raw mill machine because if the raw mill machine is damaged and causes the termination of the operating process, then other machines will also not be able to operate. Therefore, maintenance is carried out on the christis components of the raw mill 4R1 indarung IV machine. To solve the problem with PT. Semen Padang, planned scheduling of treatment using monte carlo simulation where this method is simulated by random number generation. The strategy proposed in the monte carlo simulation uses 2 scenarios, namely corrective maintenance and MTTF. The results of this study are the right maintenance strategies for raw mill machines and separators are preventive maintenance and for boom side reclaimer machines that are corrective maintenance.