Plenty　of　focus　measures　have　been　proposed　and　researched　in　the　past　few　years.　However,　little　attention　is　paid　to　their　performance　in　the　autofocus　of　line　scan　cameras.　This　paper　investigates　sixteen　typical　focus　measures,　and　their　performance　is　compared　for　the　autofocus　of　line　scan　cameras.　A　comprehensive　evaluation　method　is　proposed　to　assess　the　performance　of　focus　measures.　Subjective　evaluation　is　firstly　utilized　to　exclude　the　focus　measures　of　poor　performance.　Then,　objective　evaluation　which　includes　seven　criteria　is　utilized　to　rank　the　rest　focus　measures.　Scale　factors　are　introduced　for　the　evaluation　of　focus　measures　in　different　search　algorithms　and　focus　styles.　Experimental　results　show　that　Tenengrad　provides　the　best　performance　in　both　global-based　search　and　local-based　search　in　the　autofocus　with　auxiliary　focus　sheet.　In　the　autofocus　directly　on　the　object　when　the　object　is　variable,　autocorrelation　provides　the　best　performance　in　global-based　search　while　Tenengrad　provides　the　best　performance　in　local-based　search.　In　the　autofocus　directly　on　the　invariable　object,　the　best　focus　measure　is　related　to　image　content,　and　it　should　be　selected　in　field　test.　(C)　2016　Elsevier　GmbH.　All　rights　reserved.