The present invention discloses a catalyst for in-situ CO2 capture and coupling reduction with biomass oxidation, a preparation method therefor and an application thereof. The catalyst is applied to the coupling reaction of photocatalytic CO2 reduction and biomass oxidation. The preparation of the catalyst is to synthesize layered double hydroxides (LDHs) containing CO32− between layers by using coprecipitation method, hydrothermal method, sol-gel method and the like, wherein the chemical formula is [M1-x2+Mx3+(OH)2]x+(An−)x/n·mH2O, which has a thickness of 20-30 nm and an average particle diameter of 60-90 nm. Then metal ion vacancy defects are produced on LDHs laminate by using a NaOH/KOH selective etching to obtain the corresponding catalyst. The catalyst is used in photocatalytic reaction, characterized in that CO32− is continuously consumed in the reaction process, and the catalyst can absorb CO2 in the air for recovery after the reaction, and can be repeatedly used to continuously consume CO2 in the air, thus realizing the direct capture and effective utilization of CO2.