The effective assessment of organizational reliability, maintainability and supportability (RMS) engineering capability has an important significance to improving organizational RMS work level. For the problem of organizational RMS engineering capability assessment being complex, and many indexes being fuzzy and difficult to be defined the value and weight, a method based on fuzzy analytic hierarchy process (FAHP) was proposed to assess organizational RMS engineering capability. Firstly, the concept of organizational RMS engineering capability was defined and the index system for RMS engineering capability assessment was presented. Secondly, concrete steps of organizational RMS engineering capability assessment method based on FAHP for application of the system were introduced. Finally, the application of a case was given to verify the method effectively.