Clean　and　renewable　energy　is　the　only　way　to　achieve　sustainable　energy　development,　with　considerable　social　and　economic　benefits.　As　a　key　technology　for　clean　and　renewable　energy,　it　is　very　important　to　research　the　reliability　optimization　of　microgrids.　This　paper　reviews　the　research　progress　in　microgrid　reliability　optimization.　This　paper　first　classifies　and　summarizes　the　existing　research　on　microgrid　control　strategies　and　reliability　assessment.　Then,　the　system　reliability　optimization　framework　is　summarized　in　terms　of　both　microgrid　systems　and　optimization　objectives.　Next,　we　summarize　the　most　commonly　used　optimization　algorithms　for　microgrid　reliability　for　different　microgrid　systems.　Finally,　we　provide　a　bibliometric　analysis　of　the　literature　on　the　reliability　research　of　microgrids.　In　addition,　we　propose　some　research　challenges　in　the　future　for　the　reliability　of　microgrids.