The invention discloses a method for preparing 
alum-free vermicelli based on 
modified starch. The method comprises the following steps of: (1) preparing 
starch milk by taking 
starch as the 
raw material, and then, preparing cross-linked 
starch by taking 
phosphorus oxychloride as a cross-linking agent; (2) preparing starch milk by taking starch as the 
raw material, and then, preparing octenyl 
succinic acid modified starch by taking octenyl 
succinic anhydride as an esterifying agent; (3) preparing starch milk by taking starch as the 
raw material, and then, preparing high cross-linked starch by taking 
phosphorus oxychloride as a cross-linking agent; and (4) adding starch with a certain 
mass into water to prepare starch milk, rapidly pouring boiling water into the starch milk to prepare starchy sauce paste, adding the cross-linked starch, the octenyl 
succinic acid modified starch and the high cross-linked starch in a certain proportion, mixing and uniformly stirring the cross-linked starch, the octenyl 
succinic acid modified starch and the high cross-linked starch, placing the mixture into a vermicelli 
machine for 
extrusion forming, cooking the vermicelli for several seconds, then, rapidly placing the cooked vermicelli into cold water to cool and retrograde for several minutes, and 
drying to obtain a finished product of the vermicelli. Compared with the traditional vermicelli preparation method, the method has the advantages that no 
alum is used, the property of the vermicelli is improved, and the prepared vermicelli has favorable boiling fastness, favorable 
toughness and favorable 
retrogradation resistance.