Sea urchins play an important role in the regulation of the structure and function of the kelp bed ecosystem. Effects of flow velocity on feeding behavior and growth can improve our understanding on the ecology of sea urchins. We studied the survival, growth, feeding behaviors of the sea urchin Mesocentrotus nudus exposed to different flow velocities (2 cm/s, 10 cm/s, and 20 cm/s) over 49 days. The flow velocity significantly affected the growth of sea urchins (test diameter ~20 mm). Test diameter and body weight of sea urchins were significantly lower in the high flow velocity group, while the survival was not significantly affected. Significant differences in body weight and test diameter of sea urchins were observed in the 2^nd and 3^rd weeks after the beginning of the experiment. The long-term unidirectional water flow significantly affected food intake (P<0.001) and foraging behavior (20 cm/s, P=0.004) of M. nudus. However, Aristotle's lantern reflex was not significantly affected by flow velocity (P=0.113). Flow velocity significantly affected the adhesion of M. nudus at 10 cm/s (P < 0.001) and 20 cm/s (P < 0.001), inhibiting the foraging of sea urchins. Consistently, the flow velocity of 20 cm/s significantly weakened the righting behavior of sea urchins compared to 2 cm/s (P=0.02) and 10 cm/s (P=0.03). Therefore, the sea area with a perennial flow velocity of 2-10 cm/s is suitable for stock enhancement of sea urchins. This study provides referable flow velocity information for better understanding the ecological habits and stock enhancement requirements of sea urchins.