In order to improve the knowledge acquisition efficiency and effectiveness of ship coating process, a knowledge acquisition method based on improved item constraint association rules is proposed. First, the target data set is filtered according to the antecedent constraint and the consequent constraint to obtain the coating process knowledge in a targeted manner. Then, the constrained association rules algorithm is used to mine the rules in the coating process transaction database and filter them to obtain the association rules that satisfy the constraint conditions. Finally, the coating process knowledge is extracted from the obtained rules and stored in the knowledge base. The field test results show that the proposed method improves the performance of the algorithm while shortening the computation time. The improved item constraint association rules algorithm is superior to the traditional algorithm.