To investigate the effects of mechanical collision on the early life stages of fish that produce drifting eggs, this study used Ctenopharyngodon idella larvae as the research subject. Simulated stone plate impacts were conducted at different velocities (1.4, 3.1, and 4.4 m·s -1, designated as low, medium, and high speeds, respectively) and angles (45° and 90°). A control group receiving no impact treatment was also established. The mortality rate, heart rate, locomotor behavior, and growth and survival of the experimental fish were measured. The results show that: 1) Collision velocity significantly affected the immediate mortality and the cumulative mortality within 24 h after collision treatment ( p <0.05), and both indices increased with increasing collision velocity. 2) The heart rates of fish 24 h after treatments at all three collision velocities were significantly higher than those of the control group ( p <0.05). 3) At 24 h after collision treatment, clean water, food pheromone solution, or predator pheromone solution was added separately to the test water. Under all three test conditions, the experimental fish subjected to low- and medium-velocity impact treatments exhibited significantly higher than those of the control group and the high-velocity collision group ( p <0.05), whereas no significant differences were detected between the latter two groups. 4) Stone plate impact had no significant effect on the specific growth rate during the 14-day growth experiment initiated 24 h after collision treatment, but it significantly affected mortality during this period ( p <0.05). Moreover, mortality was higher under the 45° oblique collision than under the 90° vertical collision. These results suggest that stone plate impact may induce stress responses in grass carp larvae and increase the sensitivity of their locomotor behavior to external stimuli, while high-velocity collisions may impair their locomotor capacity. Overall, stone plate impact exerts persistent negative effects on grass carp larvae.