The invention aims to supply a process for preparing nutritious water-chestnut starch according to the above problems, which is characterized in that the steps for preparation are that: (1) Fresh water chestnut is selected and is grinded into pulp, and water is leached. (2) Through drying and sieving, the water-chestnut starch is made. (3) The effective components of carrots, tremella, jujubes, matrimony vine and mythic fungus are extracted, through concentrating, adsorbing and drying, cyclodextrin powder is made and is fully mixed with the water-chestnut starch. (4) Instant nutrition food is prepared, packaged, sealed, sterilized and is put in storage. The invention has the beneficial effects that not only the contents of sugar, proteins, calcium, phosphorus, ferrum and vitamin C of the water-chestnut starch are increased, but also nutritional components of amino-acid germanium and carotenes and the like are further increased, the food which is made through the processing method has the effects of nutrition, galangal fruit, tranquilization and health care, the eating is convenient, and the carrying is easy.