The invention discloses eucommia sweet potato powder and a preparation method thereof, wherein the eucommia sweet potato powder is prepared from the following raw materials in percentage by weight: 0.5-2.5% of eucommia leaf extractive, 96.0-98% of sweet potato starch, 0.5-1.2% of edible salt and 0.3-0.6% of food additive, and the eucommia sweet potato powder is prepared by the steps of dough kneading, extruding and curing, aging, freezing, unfreezing and vermicelli dispersing, wherein the eucommia leaf extractive is an alcohol extractive of eucommia leaves; the food additive is one or a mixture of multiple of zinc sulfate, sodium polyacrylate, acetic ester starch and sodium alginate. According to the invention, the eucommia extractive is added, thus the health care value is increased for the traditional food of sweet potato vermicelli, and the special raw material proportion and production technology can effectively maintain the effective components of the eucommia extractive, thus the product has favorable impressions and mouthfeel, has high toughness, is not messy after being cooked for a long time, and also is easier to implement vermicelli dispersing under the condition that harmful substances such as alums are not added.