Organic　solar　cells　(OSCs)　are　among　the　most　promising　photovoltaic　technologies　to　solve　energy　and　environmental　problems.　To　achieve　highly　efficient　OSCs,　controlling　over　electrode　interfacial　layers　is　greatly　important　for　improving　charge　transportation　and　collection.　Here,　ternary　metal　oxide　semiconductor　films　of　Mg-doped　NiO　(NiMgO)　have　been　prepared　via　a　sol-gel　method,　and　further　optimized　by　several　post-treatment　strategies.　The　structures,　properties　and　energy　levels　of　different　NiMgO　films　have　been　investigated　to　explore　the　influence　of　various　post-treatment　strategies.　Incorporating　the　ternary　NiMgO　films　as　a　novel　type　of　hole　transport　layers　(HTLs),　non-fullerene　OSCs　have　been　fabricated　based　on　a　promising　bulk-heterojunction　of　PM6:M36.　Their　photovoltaic　performances　and　mechanisms　of　device　physics　are　also　investigated.　When　the　sol-gel　derived　NiMgO　film　without　post-treatment　is　used　as　an　HTL,　the　OSCs　show　a　relatively　low　power　conversion　efficiency　(PCE)　of　5.90%.　By　contrast,　after　simple　ultraviolet-ozone　(UVO)　post-treatment　on　the　NiMgO　HTL,　the　resulted　OSCs　exhibit　greatly　enhanced　photovoltaic　performances,　with　an　increased　open-circuit　voltage　(V-OC)　of　0.87　V　and　an　improved　PCE　of　12.67%.　More　importantly,　a　new　dual　post-treatment　combining　surface　rinse　with　UVO　treatment　has　been　demonstrated　to　further　optimize　NiMgO　HTLs　and　improve　device　performances.　The　rinse　process　can　remove　excess　impurities　and　flatten　the　surface　of　NiMgO　films　as　well　as　increase　the　transmittance,　while　the　UVO　treatment　process　is　beneficial　for　reducing　surface　defects　of　the　ternary　oxide　films.　Benefiting　from　such　an　efficient　dual　post-treatment　on　NiMgO　HTLs,　the　OSCs　afford　a　high　PCE　of　13.17%　with　a　retained　V-OC　of　0.87　V,　an　increased　short-circuit　current　density　of　23.48　mA.cm(-2),　and　an　improved　fill　factor　of　64.29%.　These　results　provide　an　effective　way　for　surface　post-treatment　and　property　optimization　of　semiconducting　metal　oxide　films,　and　contribute　to　the　development　of　high-performance　optoelectronic　devices.