Maintenance task prioritisation is essential for production system, especially when available resources are limited. Related studies take either system safety or productivity as the objective of system maintenance prioritisation. While since improper system maintenance can make bad equipment cooperation thus induce unstable manufacturing process and big equipment operation time loss, system process ability is also necessary to be improved in production line maintenance. Therefore, the overall line efficiency (OLE) which comprehensively evaluates production line productivity and process ability is adopted as the objective to develop maintenance prioritisation in this study. Specifically, an OLE centred maintenance prioritisation policy which assigns priorities according to the influences of the specific characteristics of equipment operational reliability on OLE is proposed: To correctly allocate limited maintenance resources to truly critical equipment and achieve good maintenance effect, equipment influences on OLE are analysed from the level of the specific performances of their operational reliability: equipment mean time between stops (mtbs), mean time to resume from stops (mttr) and buffer size N. Considering the interactions between these parameters, a surrogate modelextended Fourier amplitude sensitivity test (SM-EFAST) process is integrated to accurately and rapidly analyse the total effects of them on OLE. In the end, an application case adopting the proposed OLE centred maintenance prioritisation method achieved higher OLE and lower total maintenance cost than two current popular maintenance prioritisation methods.