A　core-shell　structure　SrSO4-SrCO3　(SSO-SCO)　composite　was　synthesized　with　strontium　titanate　and　ammonium　carbonate.　The　SrTiO3-SrSO4-SrCO3　(TSC)　composite　with　core-shell　structure　was　obtained　by　adding　strontium　titanate　into　the　mixture　through　hydrothermal　method.　The　morphology,　elemental　composition　and　crystallinity　of　the　catalyst　were　characterized　by　SEM,　EDS,　TEM　and　XRD　analyses.　The　TSC　composite　exhibited　excellent　photocatalytic　performance　for　the　degradation　of　methylene　blue　dyes　compared　to　the　SrTiO3.　The　high　catalytic　efficiency　was　due　to　synergistic　effect　of　the　increased　light　harvesting　and　efficient　transport　of　photogenerated　electron　and　hole　pairs　in　composites　based　on　the　results　of　UV-vis　and　PL　and　transient　photocurrent　response　tests.　Furthermore,　ESR　spectra　showed　that　center　dot　OH　radicals　and　hole　radicals　were　the　main　active　species　contributing　to　the　excellent　performance.　Based　on　the　photocatalytic　results　and　ESR　spectra,　a　photocatalytic　mechanism　for　MB　degradation　was　proposed.