In　order　to　evaluate　the　far-field　beam　quality　of　10　kJ-level　laser　facility　with　different　off-axis　wedged　focus　lens,　by　utilizing　the　methods　of　the　sampling　of　weak　light　beams　and　amplification　imaging　of　splitting　beams,　the　focal　spot　data　of　3ω　laser　was　collected　by　two　16-bit　scientific-grade　CCD　cameras　in　the　paths　of　main　lobe　and　side　lobe　under　the　conditions　of　that　the　lateral　magnification　coefficient　is　the　same　but　the　intensity　attenuation　coefficient　is　different.　One　CCD　obtained　main　lobe　of　far-field　image,　the　other　acquired　its　side　lobe.　The　far-field　focal　spot　was　reconstructed　based　on　the　mathematical　model　of　schlieren　method,　and　the　dynamic　range　is　1　151.7∶1.　The　influence　of　CCD　dynamic　range,　relative　magnification　ratio　and　system　noise　on　reconstructed　image　was　analyzed.　Experimental　results　show　that,　the　method　can　achieve　a　high　dynamic　range　far-field　accurate　measurement　of　focal　spot,　the　stitching　error　is　less　than　one　pixel,　which　meets　the　requirements　of　targeting　experiments　in　experimental　precision.　©　2016,　Science　Press.　All　right　reserved.