Abstract: Ephemeris error is one of the most important factors which affect positioning precision when satellite navigation was used.First,taking the GPS as an example,the spectral characteristic of broadcast ephemeris error was analyzed,in which the spectral analysis method was applied.And then ephemeris errors were predicted by using the spectral analysis model and the combined model which of the AR model and the spectral analysis model.The results of research demonstrate that the GPS broadcast ephemeris has periodical wave error,the main period variations of broadcast ephemeris can be determined by the spectral analysis model though its prediction precision is not high.After compensation,the precision of ephemeris was at 0.5 meter level (1σ) when the spectral analysis and AR combined model was used.