The transmission characteristics of ultrasonic wave impinging obliquely on composite laminates are analyzed. Incorporating the influence of thin resin-rich regions between adjacent plies by spring-type interfaces, the amplitude transmission coefficient of a unidirectional composite laminate immersed in water is calculated by the stiffness-matrix method. Using Floquet's theorem, the dispersion relation for the infinitely laminated structure is also calculated. Comparison between two results reveals that the frequency band-gaps in the dispersion relation agree well with the low-transmission frequency ranges of the finite laminated case. Comparing with the experimental transmission coefficients for an 11-ply carbon-epoxy composite laminate, the theoretical results are verified.