In　order　to　improve　the　quality　and　efficiency　of　flow-layer　physical　co-design　in　Continuous-Flow　Microfluidic　Biochips　(CFMBs),　placement　and　routing　co-design　is　implemented　in　three　stages.　(1)　Placement　preprocessing　stage:　Through　the　logic　placement　and　component　orientation　placement　adjustment　method,　the　excellent　logical　position　and　logical　orientation　of　components　are　obtained.　(2)　Component　mapping　and　bounding-box　gap　placement　adjustment　stage:　Based　on　the　bounding-box　strategy,　the　placement　preprocessing　result　is　mapped　into　the　actual　physical　design　space,　and　the　optimal　bounding-box　gap　is　obtained　after　the　placement　adjustment　of　bounding-box.　(3)　Shrinking　placement　adjustment　stage:　Based　on　the　connected　graph　relationship　among　components,　two　original　placement　adjustment　methods,　shrinking　along　the　flow　channel　and　multi-graph　shrinking,　are　proposed.　The　experimental　results　show　that,　compared　with　the　existing　best　heuristic　algorithm,　the　algorithm　in　this　paper　optimize　the　chip　flow-layer　integral　area,　the　number　of　flow　channel　intersections　and　the　total　length　of　flow　channel　by　20.22%,　54.66%　and　71.62%,　respectively,　and　the　speedup　ratio　is　177.12,　which　improves　significantly　the　design　quality　and　efficiency.　©　2023　Science　Press.　All　rights　reserved.