Precision　polishing　of　small　modulus　gears　is　a　difficult　task　due　to　the　complexity　of　their　geometry.　Electrolytic　plasma　polishing　technology　as　a　green　and　efficient　processing　method,　it　can　effectively　decrease　the　friction　between　parts　and　improve　the　service　life.　However,　considering　the　uneven　distribution　of　gas　layers　on　the　surface　of　workpieces　in　electrolytic　plasma　polishing,　which　affects　the　precision　of　workpiece　shapes　after　polishing,　this　study　proposed　the　use　of　ultrasonic　vibrations　to　generate　pressure　waves　to　improve　the　fluid　characteristics.　Comparative　experiments　on　small　modulus　gear　electrolytic　plasma　polishing　with　and　without　ultrasonic　vibration　were　conducted.　A　high-speed　camera　was　utilized　to　monitor　the　distribution　of　gas　layers　around　the　workpiece　during　the　polishing　process　in　real-time.　The　optical　measurement　methods　were　used　to　evaluate　the　gear　precision.　The　results　indicate　that　ultrasonic　assistance　is　beneficial　in　improving　the　uniformity　of　the　gas　layers　surrounding　the　workpiece,　achieving　higher　gear　precision,　and　obtaining　a　lower　surface　roughness　after　polishing.　Through　orthogonal　experiments,　this　study　analyzed　the　effects　of　various　process　parameters　on　the　surface　roughness　of　gear　profiles　and　the　uniformity　of　material　removal　after　polishing.　These　parameters　included　power　voltage,　polishing　time,　workpiece　immersion　depth,　ultrasonic　frequency,　and　workpiece　posture　angle.　An　optimal　combination　of　process　parameters　was　identified.　The　results　show　that　the　best　surface　roughness　and　gear　precision　were　achieved　with　a　power　voltage　of　300　V,　a　polishing　time　of　4　min,　a　workpiece　immersion　depth　of　about　10　mm,　an　ultrasonic　frequency　of　40　kHz,　and　a　workpiece　tilt　angle　of　45　degrees.