An organocatalytic aldol reaction of cyclic hemiacetals to aldehydes was developed. As a seldom reported nucleophile in organocatalysis, cyclic hemiacetals herein provided a smooth method to approach a series of cyclic ether substrates with excellent ee value, good yields, and good to moderate diastereoselectivity. The absolute configuration and relative configuration were determined by a Mosher method and 2D NMR spectral analysis of the derivative, respectively.