Disclosed is wettable powder compounded of mancozeb and fosetyl-aluminium and a preparation method of the wettable powder. The wettable powder comprises, by mass percentage: original drugs of mancozeb and fosetyl-aluminium, a dispersant, a wetting agent, a deflocculant, a stabilizing agent, a glidant, an antifoaming agent, and a filler. The preparation method comprises: (1) weighing the following raw materials: the original drugs of mancozeb and fosetyl-aluminium, the dispersant, the wetting agent, the deflocculant, the stabilizing agent, the glidant, the antifoaming agent, and the filler, and uniformly mixing the raw materials; and (2) performing superfine grinding of the raw materials through a jet mill, grading the obtained product through a 45-micron test sieve, and uniformly mixing the obtained product. The wettable powder is simple in process, low in cost, convenient to store and transport, safe, and stable in property, has advantages of less application amount, wide bactericidal spectrum, quick effect, complete sterilization, low residue, and effective postponing of generation of a pathogen antibody, and is an excellent chemical bactericide.