The invention discloses a gahnitem, zinc oxide and nickel zinc nano-composite photocatalytic material which has a high specific surface area and a mesoporous structure and is prepared by roasting at high temperature by taking ternary hydrotalcite as a precursor. The material is used for the adsorption and the degradation of organic pollutants. The photocatalytic material is prepared by taking zinc nitrate, nickel nitrate, aluminum nitrate, sodium carbonate, sodium hydroxide and the like as raw materials; preparing the raw materials into salt solutions and alkali solutions respectively; mixing the solutions by using a constant-flow pump at the temperature of 80 DEGC with magnetic stirring, transferring the mixed solution into a hydrothermal reaction kettle; performing hydrothermal treatment at 130 to 180 DEG C; performing suction filtration, washing and drying to the precursor; roasting the precursor in Muffle furnace for 2 to 6 hours at the temperature of 400 to 600 DEG C to obtain the product, wherein the specific surface area is greater than 150 m<2>.g<-1>. The photocatalyst disclosed by the invention has regular shape, large specific surface area, and super-high capacity for adsorbing and degrading organics, and can be reused; the raw materials for preparing the composite photocatalyst are abundant, the cost is low, and the process is simple.