The invention relates to an extrusion preparation method of crosslinked cassava starch, and belongs to the technical field of foods. The method comprises the following steps: using cassava starch as a raw material, adding crosslinking agent and catalyst, extruding by using a double-screw extruder, cooling and pulverizing to obtain the crosslinked cassava starch. The sedimentation volume of the crosslinked cassava starch is 0.5-2.5. The invention produces the crosslinked cassava starch by using the extrusion method for the first time in China, and provides foundation for the application of crosslinked cassava starch in food industry.