Active　equalization　systems　require　balancing　current　regulation　to　further　improve　balancing　efficiency　and　battery　cycle　life.　This　paper　focuses　on　an　adaptive　control　strategy　for　a　battery　equalization　system　based　on　modified　isolated　Cuk　converter.　Firstly,　the　analysis　and　modeling　of　the　modified　isolated　Cuk-based　equalizer　are　presented,　and　then　the　development　of　the　adaptive　sliding-mode　control　(SMC)　scheme　is　proposed.　The　designed　controller　is　verified　through　testing　transient　response,　reference　current　variation　and　load　change　under　continuous　conduction　mode.　Compared　with　a　traditional　SMC,　the　proposed　adaptive　control　has　strongly　ability　to　cope　with　the　external　disturbance　and　system　parameters　variation.　A　bus-based　battery　equalization　system　for　five　cells　in　series　with　an　unbalanced　state-of-charge　(SOC)　0.75,　0.90,　0.45,　0.80　and　0.67　is　performed　to　test　the　proposed　control　method.　The　simulation　results　indicate　that　the　battery　pack　reaches　to　a　balanced　state　in　712　sec.　©　2019　IEEE.