In the preliminary stage of mechanical and electrical products reliability prediction, due to the lack of reliability data, the reliability prediction is expected to be difficult. But also in the design process, lots of fuzzy and uncertain information is existence. In view of this, the reliability prediction model based on triangular fuzzy number is proposed. This model is consistent with the mode of thinking, can also merge the fuzzy information very well and make the fuzzy decision . On this basis, according to the influence factors of mechanical and electrical products reliability, analytic hierarchy process (AHP) is applied to determine weights, the model of the fuzzy comprehensive evaluation is built and a new operator is introduced for the triangular fuzzy number. Therefore a more objective prediction can be expected to make for the reliability of mechanical and electrical products.