The invention discloses a method for preparing crosslinked porous cassavastarch, which is to regulate the concentration of cassavastarch suspension to a diluter range from 20 to 34.8 weight percent for facilitating cross-linking reaction, achieving high degree of crosslinking and ensuring the quality uniformity of the crosslinked starch and creating a favorable condition for subsequent enzymolysis. The prepared crosslinked porous cassavastarch has a compact molecular shell structure, is stable in structure, enzymolysis resistant, chemically stable, free from collapse, safe, nontoxic, biodegradable and widely applicable and allows the size of the aperture of the molecular network to be adjusted by processes. In the preparation method, the production process is simple, the raw material cassavastarch is rich, cheap and readily available, the production cost is low, the production scale can be adjusted flexibly and the adaptability is high. The method is applicable to common fine starch manufacturers, chemically modified starch manufactures and common food, medicine, industrial, farm chemical, pesticide manufacturers and other manufacturers.