Abstract: The theory of fuzzy probability should be applied to quality design for product because of product characteristics with both randomness and fuzziness. After the randomness and the fuzziness are analyzed and the concept of zero defect design is defined, the theory of zero defect design based on fuzzy probability is proposed and the corresponding mathematical model is built. It is proved by an example that this model can be used to improve product quality greatly and has practical application in quality design for product.