Ultraviolet and photocatalysis combined rainwater treatment system and working method thereof

The invention relates to an ultraviolet and photocatalysis combined rainwater treatment system which comprises a vegetation planting layer, wherein a gravel layer is arranged below the vegetation planting layer; a rainwater collection module is arranged below the gravel layer; a catalysis layer is arranged on the surface of the rainwater collection module; the rainwater collection module is internally provided with ultraviolet lamps capable of allowing the catalysis layer to give a photochemical reaction; the rainwater collection module is further internally provided with a water absorption belt capable of absorbing water of the rainwater collection module into the gravel layer; a water-proof geomembrane is arranged below the rainwater collection module; a support frame for supporting therainwater collection module is arranged below the geomembrane; a gravel bed layer for infiltration of excessive rainwater is arranged below the support frame; and a connecting pipe is arranged betweenthe gravel bed layer and