A　closed　loop　spray　cooling　system　with　R134　-　A　as　spray　medium　was　used　to　investigate　the　performance　of　spray　cooling　characteristic.　The　heat　transfer　parameters　such　as　heat　flux,　heat　transfer　coefficient　and　target　surface　temperature　were　studied　under　different　volumetric　flow　rate　and　spray　chamber　pressure.　The　single-phase　heat　transfer　region　and　the　phase-change　heat　transfer　region　were　analyzed　at　different　heat　fluxes.　The　results　show　that　the　heat　flux,　critical　heat　flux　(CHF)　and　heat　transfer　coefficient　directly　relate　with　volumetric　flow　rate.　The　higher　flow　rate　and　spray　chamber　pressure　could　achieve　higher　CHF　with　better　heat　transfer　performance.　And　the　different　relationship　between　heat　transfer　coefficient　and　surface　temperature　was　obtained　at　different　spray　cooling　period.