numerical model is created to study the sorting behavior of mixed-grain-size sediments in oscillatory sheet flow, including both particle-particle interaction and particle-fluid interaction. Additionally, beside this symmetry sinusoidal oscillatory flow, the sorting processes of mixed sands in asymmetry progressive cnoidal wave are also numerically investigated. The results of mixed sands under symmetric oscillatory flow show that the water particle semi-excursion is a key influence factor on the armoring effect. For the cnoidal wave, the vertical sorting proceeds until the wave crest passes by and fully develops in a complete period. The concentration centroid of large particles becomes higher landward within 2 periods.