Reliability　design　is　one　important　link　to　assure　the　product＇s　quality.　Reliability　allocation　is　the　main　task　of　reliability　design,　which　is　influenced　by　cost,　manufacturing　consistency,　and　other　factors.　Reliability,　cost,　and　manufacturing　consistency　are　coupled　and　influenced　by　each　other.　To　find　the　global　optimal　reliability　indices,　one　modeling　and　solving　method　of　reliability　allocation　based　on　multidisciplinary　design　optimization　was　proposed　in　the　paper.　The　influence　factors　of　reliability　allocation　were　analyzed　and　calculated　or　fuzzy　processed.　The　reliability　allocation　optimization　models　were　created,　and　the　models　were　decomposed　by　the　calculation　frame　of　collaborative　optimization.　The　genetic　algorithm　of　the　system-level　optimization　and　the　sequential　quadratic　programming　algorithm　of　the　disciplinary-level　optimization　were　adopted.　As　one　typical　electromechanical　equipment,　CNC　cylindrical　grinder　was　allocated　of　reliability　by　the　method　proposed　in　the　paper.　The　results　showed　that　the　cost　can　be　dropped　3.45%,　4.76%,　4.72%,　and　8.45%　compared　by　equal　allocation　method,　fuzzy　allocation　method,　AGREE　allocation　method,　and　actual　cost,　respectively.　The　reliability　allocation　method　proposed　in　the　article　can　be　used　in　design　of　electromechanical　equipment　to　reduce　costs.