The　co-burning　of　multiple　tank　fires　and　dike　fire　is　a　typical　fire　phenomenon　in　massive　fire　accidents,　which　involved　intricate　heat　and　mass　transfer　processes.　This　study　aims　to　investigate　the　dynamic　evolution　behaviors　and　explore　the　heat　feedback　characteristics　exhibited　by　co-burning　fires.　A　series　of　co-burning　fires　(CBFs)　experiments　with　different　tank　spacings　were　conducted.　For　comparison,　the　experiments　of　double　tank　fires　(DTFs)　and　dike　fire　(DF)　were　also　conducted.　The　flame　morphology　of　CBFs　shows　that　the　burning　process　can　be　divided　into　four　stages,　i.e.,　elevated　and　ground　fire　of　initial　stage,　boiling　over　stage,　quasi-stable　co-burning　stage,　and　extinguishing　stage.　During　the　quasi-stable　stage,　the　fuel　of　the　tank　is　in　film　boiling.　And　the　mass　loss　rate　of　the　tank　increases　sharply　accompanied　by　flame　lift-off　compared　with　discrete　double　tank　fires.　It　indicates　that　the　heat　feedback　enhancement　plays　a　dominant　role　due　to　the　direct　heating　of　sidewall　by　the　dike　fire.　The　analysis　of　heat　feedback　reveals　that　the　mode　of　heat　conduction　changes　and　the　dominated　heat　feedback　for　CBFs　has　shifted　from　radiation　to　conduction　compared　with　DTFs,　accounting　for　about　65　%　of　the　total　heat　feedback.　©　2025　Elsevier　Ltd