The process of product function optimization comprises a large number of uncertain function requirements and unknown function requirements.A product function optimization algorithm based on cognitive uncertain reliability is constructed to analyze the overall function of the product,probabilistic sub functions and reliability distribution,so as to select the optimal function combination that meets a set of constraints at the specified probability.The research results show that the optimization algorithm,with the high fire truck as an example,helps to accurately measure the uncertainty of product functions and control it within the expected range of customer needs,hereby ensuring product quality and reliability.