After　a　first-principles　calculation,　the　calculated　energy　gaps　of　TiO2,　MoS2　and　TiO2/MoS2　were　found　to　be　2.35eV,　1.68eV　and　1.95eV,　respectively.　The　conduction-band　bottom　of　anatase　TiO2　was　determined　by　the　electronic　distribution　of　the　Ti　(d)　orbit,　and　the　valence-band　top　of　anatase　TiO2　was　determined　by　the　electronic　distribution　of　the　O　(p)　orbit.　The　conduction-band　bottom　of　the　MoS2　was　determined　by　the　electronic　distribution　of　the　Mo　(d)　orbit,　and　the　valence-band　top　of　MoS2　was　determined　by　a　hybridization　of　S　(p)　orbit　and　Mo　(d)　orbit.　The　conduction-band　bottom　of　TiO2/MoS2　was　determined　by　a　hybridization　of　the　Mo　(d)　orbit,　the　Ti　(d)　orbit　and　the　S　(p)　orbit,　and　the　valence-band　top　of　TiO2/MoS2　was　determined　by　a　hybridization　of　the　S　(p)　orbit,　the　O　(p)　orbit　and　the　Mo　(d)　orbit.　The　MoS2　nanoflowers,　MoS2　nanorods　and　the　TiO2/MoS2　heterostructures　were　synthesised　through　a　simple　hydrothermal　procedure.　Photocatalytic　degradation　experiments　demonstrated　photodegradation　of　the　TiO2/MoS2　heterostructures　was　99.62%　for　rhodamine　B,　96.42%　for　methylene　blue　and　87.45%　for　methyl　orange.