The invention discloses a preparation method of an oat milk beverage. The preparation method comprises the following steps of using oat raw grains as raw materials, performing heat-preservation
enzyme deactivation treatment on the oat raw grains with hot water, performing
grinding with a
colloid mill, performing wet crushing, performing
liquefaction and saccharification on the crushed materials through combination of medium-temperature
amylase and saccharifying enzymes, performing heat treatment on the materials so that the space structure of oat
protein is moderately denatured, performing
centrifugal separation, and removing residues; adding
papain to the materials for modifying the oat
protein; and adding an appropriate amount of
vegetable oil and an appropriate amount of inorganic salt to obtained material liquid, performing uniform mixing with an emulsifying and dispersing
machine, performing homogenizing with a homogenizing
machine, performing superhigh-temperature instantaneous sterilization, and performing sterile filling so as to obtain oat milk. The oat milk product obtained by the method is smooth and mellow in mouth feel, milky white in color and good in
emulsion stability, other emulsifying agents or thickening agents do not need to be added, and besides, high-content soluble dietary fibers beta-
glucan are maintained, and besides, the
protein cannot be seriously denatured. The prepared oat milk can be directly drunk or can be matched with
coffee milk tea and the like for use.