The invention discloses a preparation method of broad beans pickled in vinegar. The preparation method comprises the following steps: (1) soaking broad beans till the broad beans are open, frying the broad beans, and de-oiling the broad beans; (2) wrapping the de-oiled broad beans with syrup; (3) wrapping the broad beans with a mixed powder seasoning; and (4) spraying aged vinegar to the broad beans, thereby obtaining the broad beans pickled in vinegar. Compared with the prior art, the preparation method has the advantages that through the control on the frying temperature and time and the operation of immediately cooling the fried broad beans in cold oil and the like, the broad beans taste more crisp; through the processes of wrapping the broad beans with powdered sugar and then with the mixed powder seasoning, spraying the vinegar to the broad beans and performing hot packaging in sequence, the broad beans pickled in vinegar have clear sour and sweet tastes, layered tastes and a mellow taste of aged vinegar; moreover, through matching of the broad beans, the syrup, the mixed powder seasoning and the aged vinegar, the broad beans pickled in vinegar not only have the mellow taste of aged vinegar, but also have the sour and sweet tastes meeting the requirements, thus meeting the requirement of modern people on tastes.