ABSTRACT:　Energy　level　engineering　is　a　powerful　technique　to　tune　the　electron　transport　and　the　photocatalytic　properties　of　photocatalysts　with　low-valence　Sn2+　and　high-valence　Cu2+　selfcodoping　by　solvothermal　method.　The　band　gap　energy　level　and　Fermi　level　of　Cu2ZnSnS4　nanosheets　can　be　adjusted　by　controlling　Sn2+　and　Cu2+　self-codoping　at　different　solvothermal　temperature.　This　leads　to　semiconductor　behavior　change　from　p-type　of　the　intrinsic　Cu2ZnSnS4　to　the　n-type　of　self-codoped　sample.　The　n-type　Cu2ZnSnS4　nanosheets　exhibit　a　good　CO2　photoreduction　performance　to　yield　48.14　and　25.04　mu　mol　g-1　h-1　of　CO　and　CH4,　where　CO　yields　on　n-type　Cu2ZnSnS4　is　about　4　times　higher　than　that　on　the　intrinsic　Cu2ZnSnS4.　This　work　offers　a　versatile　approach　of　different　valence　metal　ion　self-codoping　to　engineer　the　energy　level　of　multimetal　semiconductor　photocatalyst.