A preparing process of preserved plum flavor watermelon seeds is characterized by including the following steps of firstly, washing materials; secondly, preparing preserved plum flavor additives, wherein preserved plum flesh is put in water to be boiled and then put in a high-speed masher to be pulped into pulp, the pulp is added into an enzymolysis tank to be heated, clean air is blown in the enzymolysis tank, the pH of liquid in the enzymolysis tank is adjusted to be 7-8, papain is added for hydrolysis for 1-3 h, clean air is continuously blown in the enzymolysis tank in the period, compoundadditives are added into the enzymolysis tank, enzyme deactivation liquid is obtained by heating the enzymolysis tank, the obtained enzyme deactivation liquid is centrifuged and filtered to obtain enzymolysis liquid, the enzymolysis liquid is concentrated till the solid content is 70-80%, and then spraying and drying are conducted to prepare the preserved plum flavor additives; thirdly, soaking the materials, wherein 100-150 parts by weight of watermelon seeds blow-dried in the first step, 20-30 parts by weight of preserved plum flavor additives, 30-35 parts by weight of white granulated sugar, 10-15 parts by weight of dark soy sauce, 5-8 parts by weight of table salt and 250-300 parts by weight of water are put in a pot for soaking, and then the watermelon seeds are scooped up and blow-dried; fourthly, conducting drying.