Robust　performance　of　traditional　controller　for　single-phase　PV　(photovoltaic)　grid-connected　inverter　system　is　greatly　influenced　by　the　load　fluctuation.　Aiming　at　the　problems,　a　mixed　H2/H8　(H-infinity)　current　controller　is　designed　by　using　the　state　space　approach,　and　the　controller　can　ensure　that　the　system　has　good　dynamic　performance.　In　this　work,　we　exploit　multi-objective　H2/H8　robust　control　as　a　recent　and　trending　technology,　and　semidefinite　programming　(SDP)　and　linear　matrix　inequality　(LMI)　as　powerful　tools　in　research　of　the　PV　grid-connected　repetitive　control　system.　The　system　simulation　platform　is　built　on　Matlab　software,　and　by　using　modern　Matlab　toolbox　of　Yalmip　and　SeDuMi,　the　system　is　designed　based　on　output　feedback.　The　simulation　result　shows　that　mixed　H2/H8　controller　has　a　better　robustness,　which　has　a　better　inhibitory　effect　to　power　grid　load　fluctuation.　A　new　theoretical　analysis　method　for　the　practical　application　of　the　process　of　repetitive　control,　as　well　as　other　complex　process　control,　is　provided.