An　optical　system　composed　by　two　optical　elements,　both　the　lens　has　an　aspheric　curved　surface.　The　first　and　second　optical　elements　are　arranged　in　a　Galilean　configuration.　The　aspheric　surface　of　the　second　optical　element　is　related　to　the　aspheric　surface　of　the　first　optical　element　by　a　ray-tracing　function　and　of　energy　conservation.　The　input　laser　beam　has　a　first　axially-symmetric　intensity　distribution　of　Gaussian,　and　the　output　laser　beam　has　a　second　axially-symmetric　intensity　distribution　of　uniformization,　and　the　x-cross　or　y-cross　section　of　irradiance　has　flat-top　curve.　In　this　paper,　we　discuss　in　detail　the　principle　of　uniformization　and　the　related　calculation　equation　of　the　parameters　of　optical　elements,　and　solve　the　surface　sag　function　by　numerical　value　method,　then　do　fitting　calculation　of　the　aspherical　curve.　Further　more　we　analyses　this　optical　system　by　optical　design　software　Zemax,　and　show　some　figure　or　results　of　designing.　A　designing　result　about　the　aspherical　curve　parameters　of　processing　and　structure　was　given.　This　system　can　be　applied　in　400nm　similar　to　700nm,　and　except　for　this,　if　we　choose　IR　optical　material,　the　principle　of　uniformization　can　be　applied　in　IR　laser　system　too.