The　coordinated　control　problem　of　free-floating　dual-arm　space　robot　with　closed　chain　is　discussed.　First,　dynamic　equations　of　the　open-chain　space　robot　system　with　virtual　cut-off　point　are　obtained　by　Lagrangian　equation;　the　constraint　equations　of　closed　loop　are　derived　by　the　kinematics　analysis.　The　dynamic　equations　without　redundant　degree　of　freedom　of　dual-arm　space　robot　with　closed　chain　are　established　by　the　constraint　equations　and　the　theory　of　pseudo-inverse.　Second,　in　order　to　achieve　excellent　tracking　performance,　the　robust　control　based　on　extended　state　observer　is　proposed　for　the　closed-chain　system　with　uncertain　inertial　parameters.　The　unknown　part　of　the　closed-chain　system　is　compensated　by　an　extended　state　observer.　The　global　uniform　ultimate　boundedness　stability　with　exponential　convergence　is　proven　by　the　Lyapunov＇s　theory.　For　the　existence　of　the　controller　redundancy,　based　on　the　weighted　minimum-norm　theory　and　pseudo-inverse　theory,　the　joint　inputs　are　distributed　for　each　joint　to　guarantee　the　uniqueness　of　joints　trajectory.　At　last,　the　numerical　simulation　is　conducted　to　verify　the　effectiveness　of　the　proposed　control　scheme.