The invention discloses a preparation method for a broad bean milk beverage. The method comprises the following steps: (1) pretreatment of a raw material; (2) gelatinization; (3) liquefaction; (4) slurry residue separation; (5) mixing blending; (6) homogenizing; (7) filling; (8) sterilization; and (9) cooling. According to the present invention, based on the characteristic of the high starch content in the broad bean, the starch in the raw material broad bean is subjected to partial hydrolysis by using amylase, and processes of centrifugal filtration, homogenizing, sterilization, filling and the like are adopted to produce the broad bean milk beverage. The method of the present invention has the following advantages that: the starch in the raw material broad bean is subjected to partial hydrolysis, such that the stability of the resulting broad bean milk is improved, and the utilization rate of the raw material is improved.