Isopropanol　and　isobutanol　are　potentially　partial　substitutes　for　gasoline.　The　critical　properties　of　isoalcohol-gasoline　blends　are　of　great　importance　to　optimize　their　combustion　and　emission　performance　in　engines.　In　this　paper,　the　critical　temperature　(T-c)　and　critical　pressure　(p(c))　of　eight　miscible　systems　(isopropanol/isobutanol　+　n-hexane,　isopropanol/isobutanol　+　n-heptane,　isopropanol/isobutanol　+　n-octane,　isopropanol/isobutanol　+　n-heptane　+　isooctane)　were　measured　by　the　flow　method　in　the　range　of　497.69-569.21　K　and　2.495-4.766　MPa.　Experimental　results　show　that　the　addition　of　isopropanol　and　isobutanol　can　significantly　reduce　the　T-c　of　C-6-C-8　alkanes　by　0-60.85　K　and　increase　the　pc　by　0-2.271　MPa.　A　model　for　calculating　the　T-c　and　p(c)　of　these　mixtures　is　presented　based　on　the　Redlich-Kister　equations.　The　maximum　average　absolute　relative　deviations　of　the　T-c　and　p(c)　are　0.08%　and　0.46%,　respectively.