The invention relates to a preparation method of cumyl peroxyneodecanoate. The preparation method comprises the steps of: (1) using 27wt% of a hydrogen peroxide solution, 46wt% of ionic membrane liquid potassium hydroxide and chloro ester as raw materials, feeding the raw materials synchronously, and performing a stirring reaction for 30 minutes at room temperature and constant pressure; and (2) after the reaction is completed, stopping stirring, standing for 20-40 minutes, enabling oil-phase substances to be separated from an aqueous phase, and collecting oil-phase substances. In the step (1), the mass ratio of the 27wt% of hydrogen peroxide solution to the 46wt% of ionic membrane liquid potassium hydroxide and the chloro ester is (1.4-1.6): 1: (1.2-1.5). According to the preparation method disclosed by the invention, the 27wt% of hydrogen peroxide solution, and the 46wt% of onic membrane liquid potassium hydroxide are used for replacing 27wt% of cumene hydroperoxide and solid potassium hydroxide, and after reaction raw materials are changed, impurities of the raw materials are substantially reduced, so that the cost is reduced by 1000 yuan/ton.