In　this　paper,　the　steam　condensation　mixed　with　nitrogen　is　experimentally　investigated　to　examine　the　effect　of　non-condensable　gas　on　the　steam　condensation　process　at　high　speed.　The　mass　flux　of　steam/nitrogen　mixture　is　in　the　range　of　159.2-464.6　kg/(m(2).s),　the　nitrogen　mass　fraction　is　up　to　10%,　and　the　inlet　pressure　ranges　between　0.15　and　0.47　MPa.　The　mass　flow　rate　of　cooling　water　varies　from　300　to　900　kg/h.　The　effects　of　mass　flow　rate　of　cooling　water,　nitrogen　mass　fraction,　mass　flux　of　steam/nitrogen　mixture　and　channel　configuration　are　studied.　It　is　found　that　the　increase　of　mass　flux　of　mixture　increases　the　condensation　heat　flux,　the　condensation　heat　transfer　coefficient　and　the　overall　heat　transfer　coefficient.　Including　the　nitrogen　into　steam　deteriorates　the　condensation　process,　but　the　influence　of　nitrogen　on　the　condensation　process　at　high　speed　is　much　smaller　compared　to　that　at　low　speed.　The　increase　of　mass　flow　rate　of　cooling　water　promotes　the　condensation　heat　flux　and　the　overall　heat　transfer　coefficient,　but　decreases　the　local　condensation　heat　transfer　coefficient.　The　channel　configuration　and　the　gravity　has　little　effect　on　the　high-speed　condensation.　Finally,　a　new　fitting　correlation　is　proposed　to　predict　the　high-speed　steam　condensation　in　the　presence　of　nitrogen　based　on　Shah＇s　correlation.