Microchannel　manufacturing　is　one　of　the　fastest-growing　areas　in　advanced　manufacturing　with　numerous　applications,　including　turbine　blade　cooling　structures,　compact　microchannel　heat　exchangers,　and　electronic　cooling　devices.　Recent　development　of　metallic　additive　manufacturing　based　on　direct　metal　laser　sintering　technology　is　capable　of　fabricating　micro-scale　structures　with　high　complexity　and　design　flexibility.　However,　powder　bed　laser　sintering　process　produces　rough　surface　characteristics　caused　by　hatch　overlaps　and　particle　attachments,　leading　to　channel　size　reductions　and　rough　surfaces.　In　this　paper,　dimensional　metrology　of　crosssectional　views　of　multi-row　microchannels　made　by　additive　manufacturing　was　conducted　by　a　scanning　electron　microscope　at　different　locations　along　the　printing　direction.　Channel　size　reduction,　surface　roughness　and　circularity　tolerance　of　the　as-printed　channels　were　analyzed　based　on　micrographs　captured　by　SEM.　Results　showed　that　both　channel　sizes　and　hole　pitches　affected　the　printing　qualities　of　microchannels.　The　as-printed　channel　sizes　reduced　by　more　than　15%　compared　to　the　designed　values.　Two　approaches　were　made　in　this　paper　to　improve　printing　qualities.　The　first　one　was　to　redesign　channel　size　in　CAD　model　to　make　the　asprinted　channel　sizes　closer　to　the　objective　values.　Electrochemical　polishing　was　then　applied　as　a　second　way　using　sulfuric　acid　solutions.　Surface　roughness　value　was　reduced　by　more　than　40%　after　the　ECP　process.　Copyright　©　2020　ASME.