Based on the macrobenthic samples collected from 9 mid-tidal sites (3 in sandy beaches and 6 in gravel beaches) in Sanya Bay, Dongmaozhou and Ximaozhou Island in March 2014, the influences of the sediment type on ecological functions of macrobenthos were studied. The results showed that ① low mobility, burrower and filter-feeder were more in sandy beaches, however, the none and high mobility, sessile, surface crawler/swimmer, herbivore and predator-feeder were more observed in gravel beaches; ② canonical analysis of principal coordinates (CAP) showed that different sediments had different trait patterns, and mobility, habitat and feeding mode were the main factors for the differences; ③ both Shannon-Wiener index and functional diversity were generally higher in gravel beaches than those in sandy beaches; ④ the functional redundancy was all high, however, it was higher in sandy beaches than in gravel beaches.