The　research　on　information　hiding　theory　is　drawing　more　and　more　enthusiasm　in　recent　times.　This　paper　tries　to　solve　theoretical　problems　about　information　hiding　using　vector　space　methods.　Firstly,　we　project　information　hiding　system　into　vector　space.　Then　we　give　the　significations　of　imperceptibility,　embedding　intensity,　attack　intensity　and　robustness　in　multi-dimension　space.　Subsequently,　the　existence　theorem　of　information　hiding　system　is　given　and　proved.　Finally　the　upper　bound　of　capacity　is　given.　All　of　them　provide　a　novel　method　to　the　analysis　and　development　of　information　hiding　system.