The invention discloses a preparation method and device for a bottom blowing type photocatalytic porous permeable brick. The preparation device for the bottom blowing type photocatalytic porous permeable brick is characterized by comprising a forming die, a breathable end cover, a porous lining board, a draw bar, a nylon mesh, an air inlet pipe and a water draining pipe. The preparation method for the bottom blowing type photocatalytic porous permeable brick comprises the following steps: (1) smashing straw into particles with the length of 1-2cm; (2) putting the straw particles into a water glass solution to be soaked for 30 minutes, then taking out, and drying; (3) soaking in tung oil for 5 minutes, and then drying; (4) uniformly mixing the straw particles, cement, river sand, water glass, chopped fiber glass filaments, a cement foaming agent and water; (5) pouring mixed slurry into the forming die, and introducing CO2 gas at the temperature of 80 DEG C for curing; (6) drying for 5-7 days; (7) carrying out heat preservation on a porous brick for 1 hour at the temperature of 150 DEG C, slowly heating to 400 DEG C, carrying out heat preservation for 5 hours, and carrying out furnace cooling; and (8) impregnating and drawing a porous permeable brick in a photocatalytic plating solution for 5 minutes and then drying, and repeating for 3-4 times, so that the photocatalytic porous permeable brick is obtained.