Aiming　at　the　problem　of　balancing　control　of　a　cubical　robot,　this　paper　makes　a　research　on　the　balancing　control　of　a　cubical　robot　balancing　on　its　corner.　Using　the　physical　prototype　of　cubical　robot　we　designed　as　the　research　object,　the　dynamic　model　is　derived　with　Lagrangian　method.　A　balancing　controller　is　proposed　base　on　a　nonlinear　control　method-active　disturbance　rejection　control　(ADRC).　There　are　three　ADRC　controllers　in　pitch,　roll　and　yaw　direction.　The　internal　and　external　disturbance　of　the　system　are　regarded　as　the　total　disturbances　of　the　ADRC　controller.　The　effectiveness　of　the　controller　is　verified　in　the　comparison　with　PID　algorithm　with　the　obtained　expect　effect.　The　controller　developed　can　provide　a　base　for　further　study　for　balancing　control　of　a　physical　prototype　cubical　robot.