The　platooning　of　automated　vehicles　has　potential　to　significantly　benefit　road　traffic,　while　its　robust　performance　is　less　investigated　especially　considering　increasing　complexity　of　interaction　topologies.　This　study　presents　a　decoupled　H　control　method　for　automated　vehicular　platoon　to　comprehensively　compromise　multiple　performances.　The　platoon　control　system　is　first　decomposed　into　an　uncertain　part　and　a　diagonal　nominal　system　through　the　linear　transformation,　which　is　motivated　by　the　eigenvalue　decomposition　of　information　topology.　Based　on　this　almost　decoupled　system,　a　distributed　H　controller　is　presented,　which　can　balance　the　performances　of　robustness　and　disturbance　attenuation　ability.　Moreover,　a　numerical　method　is　given　to　solve　and　optimise　this　controller　by　using　linear　matrix　inequality　approach.　Several　comparative　hardware-in-loop　tests　of　different　communication　topologies　and　controllers　have　been　carried　out　to　demonstrate　the　effectiveness　of　this　method.