Withthe advance ofthesociety and economy

land is decreasing rapidly.Governmentneedsexactand quan titative data aboutlanduse statusto make reasonable decisions. However

traditional methods concerning dynamic moni toring oflanduse havelow efficiency and poor precision .Therefore

a better method tosolvethis problem isneeded .The developmentof Space Science gives us a chance. Remote Sensing can forwardly find the changed regions

Global Posi tioning System can determinethe accuratelocations oftheregions

and GeographicalInformation System can manage vari ous data asa platform .GPScan notonlyserve asan auxiliary positioning meansafterhavingfoundthetargetregionsfrom remote sensing data

butalso actas an independent data acquisition method .This paperfirstlyintroduces several basic GPSpositioning methods and their precision

and then

discusses the requirements of dynamic monitoring oflanduse at countylevel

which decidesthe modelselection of GPSreceiverand working pattern of GPS’outdoorsurveying .Combin ing a key projectof“the Ninth Five year Plan”

the authors describefive kindsof GPSacquiring data methods with com prehensive consideration of GIS’functions.The disadvantageoussurveyingconditions willleadthecreation of“2Dabnor mal data”

which can notreflectthetrue world. Deletingthe “2Dabnormal data”from original data set can provide an alternative with good authenticity.Deletingthe “2Dabnormal data”meansthe loss of acquired data.But under certain conditions

thisloss will notaffectthe computation results’precision and reality.The data acquired by GPSreceiversis based on WGS 84

but our basic databaseis on Beijing 54 .Rationalresolventis “true 54”theoretically.Here

“pseu do 54”thoughtis proposed and proved feasible in Jiaoqu County

Baotou City by a large number oftests.The conclu sions could effectivelyimprovethe efficiency ofindoorand outdoor work

and improve data precision .