Purpose　This　paper　aims　to　address　the　problem　of　uncertain　product　quality　in　digital　light　processing　(DLP)　three-dimensional　(3D)　printing,　a　scheme　is　proposed　to　qualitatively　estimate　whether　a　layer　is　printed　with　the　qualified　quality　or　not　cured　.　Design/methodology/approach　A　thermochromic　pigment　whose　color　fades　at　45　degrees　C　is　prepared　as　the　indicator　and　it　is　mixed　with　the　resin.　A　visual　surveillance　framework　is　proposed　to　monitor　the　visual　variation　in　a　period　of　the　entire　curing　process.　The　exposure　region　is　divided　into　30　x　30　sub-regions;　gray-level　variation　curves　(curing　curves)　in　all　sub-regions　are　classified　as　normal　or　abnormal　and　a　corresponding　printing　control　strategy　is　designed　to　improve　the　percentage　of　qualified　printed　objects.　Findings　The　temperature　variation　caused　by　the　releasing　reaction　heat　on　the　exposure　surface　is　consistent　in　different　regions　under　the　homogenized　light　intensity.　The　temperature　in　depth　begins　to　rise　at　different　times.　The　temperature　in　the　regions　near　the　light　source　rises　earlier,　and　that　far　from　the　light　source　rises　later.　Thus,　the　color　of　resin　mixed　with　the　thermochromic　pigment　fades　gradually　over　a　period　of　the　entire　solidification　process.　The　color　variation　in　the　regions　with　defects　of　bubbles,　insufficient　material　filling,　etc.,　is　much　different　from　that　in　the　normal　curing　regions.　Originality/value　A　temperature-sensitive　organic　chromatic　chemical　pigment　is　prepared　to　present　the　visual　variation　over　a　period　of　the　entire　curing　process.　A　novel　3D　printing　scheme　with　visual　surveillance　is　proposed　to　monitor　the　layer-wise　curing　quality　and　to　timely　stop　the　possible　unqualified　printing　resulted　from　bubbles,　insufficient　material　filling,　etc.