Impacts of different pH levels on different species of marine copepods, Calanoida copepod Schmackeria poplesia and Cyclopoida copepod Oithona similis were evaluated, and the alteration of key physiological processes of feeding and filtering were comparatively studies under controlled lab conditions. The optimal pH for O.similis and S.poplesia was 9.0 and 8.0 respectively, and they performed differently when exposed to different pH levels. For S. poplesia., the feeding and filtering rates increased steadily with the increment of pH at the range of 6.0~8.0, and reached the peak at pH 8.0. However, the rates decreased when pH was above 9.0. O.similis seemed more adaptive to the change of pH, and the increment was found in feeding and filtering rates at a range of 6.0~8.0. The maximus appeared at pH 9.0. compared to the other pH levels, the acidifying level of pH 6.0 presented the most obviously inhibition on feeding and filtering. Results in the present study would shed light on establishing the optimum culturing conditions for the cultivation of marine copepod.