简介：TheRelationshipbetweensexratioatage0to4andaltitudeinChinaisquantitativelyinvestigatedbyusingGeographicalInformationSystem(GIS)technologyinthispaper.Theresultsshowthatthecountieswithhighsexratioatage0to4in1990and2000aremainlydistributedontheeastofthewell-knownChinesepopulationdivision,Anhui-Tengchongline,andthereishighnegativecorrelationbetweensexratioatage0to4andaltitudeinChinesecounties.Therearehighestsexratioatage0to4intheregionsunder100meters,butthisratioover3200metersfallsintothenormalrange.Andthesexratioatage0to4continuestofalldownwhenthealtituderises.Sothegeographicalenvironmentevidentlyaffectsthesexratioatbirth.Thereishighersexratioatbirthinlower-altituderegions.Theeffectwithaltitudemaybeassociatedwiththeambienttempeture.