Decomposition　of　formaldehyde　with　non-thermal　plasma　was　studied　in　the　paper.　The　relationships　between　formaldehyde　removal　efficiency　and　applied　voltage,　initial　concentration,　velocity　of　flow,　supplied　power　were　mainly　investigated.　The　removal　mechanize　of　formaldehyde　was　studied　in　the　plasma.　The　experimental　results　showed　that　the　removal　efficiency　of　formaldehyde　increased　with　increasing　applied　voltage　and　power,　and　increased　with　decreasing　initial　concentration　and　velocity　of　flow　under　the　same　conditions.　At　the　same　time,　absolute　removal　quality　of　formaldehyde　increased　with　increasing　applied　voltage　and　power,　initial　concentration　and　velocity　of　flow.　Under　experimental　conditions,　the　power　of　0.092kWh　applied　to　remove　formaldehyde　per　milligram.