The invention relates to a method for producing an oat solid beverage, belonging to the manufacture field of solid beverages. The production method comprises the following steps: grinding oats into 60-80 meshes by a dry method; adding 3-15 times of water by mass in a pasting tank or a saccharifying tank provided with a stirrer; adding 5-20 thousand U/kg of high-temperature resistant amylase of oat powder; heating to boil and keeping the temperature for 10-60min; lowering the temperature to 45-60 DEG C, adding 2-12 thousand U/kg of pectase of oat powder; filtering to obtain primary filter liquid and filter residual; adding 1-4 times of water in the filter residual; soaping for 10-40min for secondary filtering; merging the primary filter liquid and the secondary filter liquid; carrying out vacuum concentration until soluble solid matter reaches more than 40%; atomizing and drying to obtain the oat beverage power; adding 20-40% of auxiliary materials by weight of oat power; and palletizing to obtain the pellet oat solid beverage. The oat solid beverage produced in the invention has the advantages of special flavor and taste of oats, smooth taste, uniform milk white color, good product stability, no precipitation or stratification within one day after being poured, abundant nutrition and content of beta-glucosan being as high as 6%.