Air Jet Loom (AJL) is a critical machine in textile industries, used to convert thread into fabric. This research used a leading textile company in Yogyakarta as a case study. Preliminary observation in the case study showed that the AJL machine had a high downtime that affects the overall production process. This study aimed to identify critical components of AJL machine and designed maintenance system for AJL machine to reduce downtime. Reliability centered maintenance (RCM) method was used in designing maintenance system by focusing on improving machine reliability. The study began with the identification of critical components of AJL machine using a fishbone diagram and continued with pareto diagram. For each critical component, time between failure (TBF) data was collected. The collected TBF data was then used to calculate the level of reliability and maintenance schedule. The results found that there were six critical components of AJL machine, i.e., VPM, take up, insertion, kamran, oil circulation, and leno. The preventive maintenance scheduling interval for the six components was VPM 120 hours, belt take up 144 hours, insertion 72 hours, kamran 24 hours, oil circulation 144 hours and leno 96 hours. The proposed preventive maintenance schedule on the six critical components of AJL machine was able to reduce downtime by 30% and increase fabric production by 13%.