When　thin　film　resistors　are　directly　written　by　laser,　auxiliary　material　can　cause　impurity　pollution.　Thickness　and　roughness　of　the　film　cannot　be　reduced　easily.　To　reduce　impurity　pollution,　film　thickness,　roughness　and　improve　the　performance　of　microcircuit　directly　written　by　laser,　the　research　of　metallic　film　resistors　directly　written　by　transmissive　laser　is　carried　out.　The　characteristic　relation　of　laser　spot　energy　distribution　and　film　line　width　is　analyzed.　The　conductive　film　of　line　width　less　than　spot　dimension　can　be　obtained.　The　experimental　results　show　that　the　increase　of　scanning　speed　or　the　decrease　of　defocusing　amount　can　lead　to　the　decline　of　overlapping　coefficient　of　spot　and　line　width　decline.　Meanwhile,　excessively　high　laser　power　can　lead　to　ablative　damage　to　thin　film;　excessively　low　laser　power　cannot　melt　the　powder　on　the　glass　substrate.　With　different　powders　in　the　process,　it　is　known　that　Zn　powder　can　form　a　uniform　thin　film　while　Al/Zn　powder　cannot　form　a　uniform　thin　film.