USB　device　interlace　oil　the　PXA270　processor　is　designed　on　demand　of　data　transmission　for　portable　spectrometer.　Analyzing　gadget　system　architecture　in　Linux　system,　USB　device　driver　is　realized,　and　the　function　of　mass　storage　provided　by　gadget　is　used　for　spectrometer　to　compliment　its　function　of　USB　storage　device,　so　that　spectral　data　file　can　be　transferred　easily　from　portable　spectrometer　to　personal　computer.　By　test,　this　USB　device　interface　works　correctly.