Biomass-synthesized　biochar　has　abundant　pore　structure,　large　specific　surface　area,　and　strong　adsorption　capacity.　Phase　change　materials　(PCMs)　have　obvious　advantages　in　using　clean　energy　and　improving　energy　efficiency.　Biochar-based　composite　PCMs　use　the　abundant　pore　structure　of　the　biochar　to　efficiently　encap-sulate　PCMs,　which　not　only　achieve　carbon　sequestration　but　also　have　broad　application　prospects　in　the　fields　of　solar　energy　usage,　energy-saving　buildings,　and　environmental　temperature　control.　This　review　summarizes　the　synthesis　of　biochar　and　biochar-based　composite　PCMs　in　detail,　as　well　as　their　application.　Importantly,　the　prospect　of　biochar-based　composite　PCMs　development　is　presented.　This　review　will　provide　references　for　advancing　the　study　of　biochar-based　composite　PCMs,　which　are　crucial　for　resource　recycling,　as　well　as　green　and　low-carbon　development.