A preparation method of filter element for swift and highly efficient adsorption of Cs includes the following steps: to a substrate material, adding a coupling agent with 1-3 wt % and ammonium phosphomolybdate with 1-10 wt %, based on the weight of the substrate material; heating to 160˜220° C.; stirring and mixing evenly so that the substrate material is combined with ammonium phosphomolybdate; spining through 5 μm micropore, the spun filament forming adsorbent filter element with a thickness of 5˜50 mm in the rotational cylinder framework material; evenly coating ammonium phosphomolybdate on the outer surface of the adsorbent filter element; and stabilizing and implementing an aging process by heating to 80˜120° C. for 3-12 h. The filter element prepared by this method provides an excellent water permeability, oxidization resistance, long-term immersion in hot water of below 100° C., radiation decomposition resistance, stable adsorption, swift detection, high efficiency and precision.