The invention relates to a photocatalyst, in particular to a preparation method of a PMMA/PPy palladium-silver photocatalyst, which comprises the following steps: uniformly mixing toluene, acetone andN-methyl pyrrolidone to prepare a microemulsion, and averagely dividing the microemulsion into two parts; adding polypyrrole and PMMA (polymethyl methacrylate) into one part of the microemulsion, andconducting ultrasonic dissolving; adding palladium chloride and silver nitrate into the other part of the microemulsion, conducting stirring and dissolving, and conducting heating and standing; mixing the two solutions, carrying out ultrasonic dispersion, and dropwise adding a urea solution; carrying out hydrothermal reaction on the mixed solution; and filtering the above product, and conductingwashing and drying. The prepared PMMA/PPy palladium-silver photocatalyst is high in visible light utilization rate, high in catalytic efficiency and long in cycle service life.