Through　measuring　lighting　performance　of　the　light-pipe　on　three　typical　weathers　in　summer,　the　luminous　flux　and　indoor　illumination　distribution　have　been　obtained.　Comparing　with　the　results　of　winter,　the　main　influence　factors　for　lighting　performance　of　light　pipe　have　been　analyzed.　The　testing　data　indicate　that　the　value　of　indoor　luminous　flux　on　sunshine　in　summer　is　4　times　more　than　in　winter,　and　it＇s　on　cloudy　and　overcast　in　summer　is　2　to　3　times　more　than　in　winter.　Through　the　comparison　and　analysis,　it　was　proved　that　seasonal　changes　greatly　impact　on　the　amount　of　light　transmission,　and　the　distribution　of　the　indoor　illumination　is　greatly　affected　by　the　solar　altitude.