NOVELTY - Light conversion and enhanced type solar photo-catalytic water splitting system and hydrogen preparing system comprises e.g. a solar light collecting-transmitting unit, which further comprises e.g. a optical fiber (2). A light switching-catalytic hydrogen preparation reaction unit, which further comprises e.g. a reactor tank (A), a light switching-catalytic hydrogen preparation reaction array (4) and a connector (3) and a light switching-catalytic oxygen preparation reaction unit, which further comprises e.g. a light switching-catalytic oxygen preparation reaction array (5).    USE - Used as a light conversion and enhanced type solar photo-catalytic water splitting system and hydrogen preparing system.    ADVANTAGE - The system: has simple structure, strong design, high photon conversion effect and stable performance; can be fully converted to adapt different usage of solar energy and solar lighting conditions and easy to carry on large-scale promotion and application.    DETAILED DESCRIPTION - Light conversion and enhanced type solar photo-catalytic water splitting system and hydrogen preparing system comprises a solar light collecting-transmitting unit, a light switching-catalytic hydrogen preparation reaction unit, a light switching-catalytic oxygen preparation reaction unit and a circulating medium controlling unit. The solar light is collected and transmitted through the solar light collecting-transmitting unit and injected to the light switching-catalytic hydrogen preparation reaction unit and the light switching-catalytic oxygen preparation reaction unit, thus interacts with the reaction medium and the light-catalyzing hydrogen preparation reaction occurs. The solar light collecting-transmitting unit comprises a Fresnel lens, a light gathering machine, an automatic solar energy tracking machine and a optical fiber (2); the Fresnel lens is arranged above the light gathering machine; the bottom of the light gathering machine is connected with the optical fiber; the light switching-catalytic hydrogen preparation reaction unit is connected with the output end of the optical fiber through the connector at the light switching-catalytic hydrogen preparation reaction array interference and connects with a hydrogen storing device through a hydrogen conveying pipe on the upper part of the reactor tank. The light switching-catalytic hydrogen preparation reaction unit further comprises a reactor tank (A), a light switching-catalytic hydrogen preparation reaction array (4), a connector (3), a gas separating film and a reaction medium. The light switching-catalytic oxygen preparation reaction unit comprises a reactor tank, a light switching-catalytic oxygen preparation reaction array (5), the connector, the reaction medium and the gas separation film; the reaction medium is connected with the output end of the optical fiber of the solar light collecting-transmitting unit through the connector at the light switching-catalytic oxygen preparation reaction array interference; the light switching-catalytic hydrogen preparation reaction unit and the light switching-catalytic oxygen preparation reaction unit perform circulating exchange and concentration control of the reaction medium through the circulating medium controlling unit; the light switching-catalytic hydrogen preparation reaction array is made of a light switching-catalytic hydrogen preparation composite material and designed according to the requirement; the light switching-catalytic oxygen preparation reaction array is made of a light switching-catalytic oxygen preparation composite material and designed according to the requirement.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of system.    Reactor tank (A)    Optical fiber (2)    Connector (3)    Light switching-catalytic hydrogen preparation reaction array (4)    Light switching-catalytic oxygen preparation reaction array (5)