Determining the position of an object on Earth＇s surface has many applications, such as in navigation and in remote sensing. The location system generally consists of a number of spatially well separated receivers that capture the radiated or reflected signal from the object. The satellite positioning systems has the advantage of long-distance and wide coverage compared with ground positioning systems and airplane positioning systems. When satellite positioning systems locates an object on earth＇s surface, TDOA （Time Difference Of Arrival） measurements, but when there are relative motions between object and satellite, the FDOA （Frequency Difference Of Arrival） can also be measured. When the altitude from sea-level of object is known, WGS-84 ellipsoid earth model can be used as the precise location model. This paper puts forwards the location algorithm for emitter on Earth using the TDOA and FDOA measurements of two low-orbit satellite, and studies in detail this algorithm, at the same time provides the error distributions model of location accuracy.