The invention relates to a preparation method of polyphenylene sulfide superfine fiber. The preparation method comprises the following steps: uniformly mixing fiber-grade polyphenylene sulfide with polyamide; melting, blending and spinning under the technological condition of not only controlling PPS (Polyphenylene Sulfide) to be molten for processing, but also enabling PA (Polyamide) not to decompose, placing the obtained polyphenylene sulfide/polyamide blended sea-island fiber in an organic solvent; and enabling the polyamine to dissolve in the corresponding organic solvent under the normal temperature condition to obtain the polyphenylene sulfide superfine fiber with a diameter range of 20nm-400nm. The preparation method of the polyphenylene sulfide superfine fiber disclosed by the invention is simple and efficient, free of a third component compatilizer, low in peel-off temperature, low in bath ratio, high in peel-off efficiency, small in energy consumption and capable of carrying out peeling completely. Moreover, the superfine fiber has the characteristics including strong adsorption capacity, softness, high temperature resistance, flame resistance, solvent resistance, high strength and the like.