A novel HOTf-catalyzed three-component one-pot cycloaddition of alpha-diazo ester, nitrosobenzene and electron deficient alkene has been developed. This catalysis is very simple to operate and tolerant to moisture/oxygen to afford the product with high to excellent diastereoselectivity in good to excellent yield, thus providing a useful and convenient method for the preparation of diverse functionalized isoxazolidines under very mild conditions.