Microfluidics　is　a　crucial　technology　in　biological　and　medical　fields,　and　its　traditional　fabrication　methods　include　soft　photolithography　poly(dimethyl　siloxane)　(PDMS)　technology　and　polymethyl　methacrylate　(PMMA)　injection　moulding　technology.　However,　these　techniques　face　challenges　in　manual　alignment　and　bonding　issues　when　they　are　used　to　manufacture　microfluidic　chips　with　complex　flow　channels.　To　overcome　these　limitations,　digital　light　processor　(DLP)　3D　printing　technology　has　been　proposed　as　a　promising　alternative.　However,　this　method　is　prone　to　problems　such　as　channel　blockage　or　shape　distortion　caused　by　the　optical　proximity　effect　or　curing　light　transmission　during　the　manufacture　of　microfluidic　chips　with　small-diameter　channels.　This　paper　introduces　a　method　to　enhance　the　manufacturing　technology　by　controlling　the　local　greyscale　of　the　projection　image　during　DLP　3D　printing.　This　allows　for　modulation　of　the　curing　light　intensity,　thus　reducing　the　optical　proximity　effect　and　the　impact　of　transmitted　light　on　extra　areas.　The　methodology　can　be　employed　in　the　production　of　microfluidic　devices　with　circular　and　square　apertures　in　the　microchannels,　utilizing　commercially　accessible　general-purpose　resins　that　are　readily　available　in　the　market.　The　printed　microfluidic　devices　show　improved　quality,　with　a　channel　size　that　closely　matches　the　preset　size,　in　contrast　to　significant　channel　blockage　in　devices　printed　without　greyscale　optimization.　This　method　provides　a　new　approach　for　enhancing　the　quality　of　low-cost　microfluidic　chip　production　and　improves　the　print　quality　based　on　the　resolution　of　the　printer　and　resin　used.　©　2023,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　London　Ltd.,　part　of　Springer　Nature.