Abstract: This paper compares static GIS, mobile GIS, dynamic GIS and moving GIS, then puts forward and discusses a description means of mobile objects, a model of spatial relation based on 9-intersection model and the query and analysis operations that moving GIS should implement. On the basis of the above theory, this paper designs the structure of moving GIS and implements a prototype system named PNS-I on the basis of PDA which has integrated GPS, GIS, GSM and GPRS.