In response to the problem of traditional similarity analysis method that are difficult to accurately quantitatively evaluate the degree of difference and low reliability between the target product and similar products, this paper proposes two new reliability prediction methods for civil aircraft electronic equipment, taking into account the similarity level and sample size of the product. A method of using interval analytic hierarchy process (AHP) to determine reliability correction factor can quantify fuzzy information and improve the accuracy of expected result.One approach is to use handbook or physics of failure (PoF) model to determine reliability correction factor, as well as introduce the concept of correlation between equipment importance level and confidence, to achieve small sample size classification for product reliability prediction, improving the accuracy and credibility of similarity analysis method.