Abstract: To choose the proper type of water-lifting aerator for more effective in situ algae inhibition, a numerical simulation method based on Fluent software was developed for hydrodynamics and water quality of reservoirs. The effectiveness of algae inhibition using submerged and non-submerged water-lifting aerators was predicted under various conditions of temperature gradient and water depth. Taking the water quality improvement using water-lifting aeration technique in Jinpen reservoir as a study case, the flow field and process of mixing of algae were numerically simulated. The simulated results of vertical velocity and algae concentration agreed well with the field data. Under typical operational conditions of a water-lifting aerator, when the water depths were 77.25,7.25 and 97.25 m, the flow outside any water-lifting aerator was characterized as one large clockwise circulation under stable state. However, the circulated flow was developed further for the submerged case. The algae with an initial average concentration in the surface area was finally reduced by 86.8%, 88.2% and 90.6% respectively, and this was not sensitive to the type of water-lifting aerator. The percentages of the core algae inhibition zone to the whole flow domain were 39.71%, 41.14% and 42.73% for the submerged cases respectively, which were 14.81%, 8.95% and 2.69% larger than those for the non-submerged cases. The periods required for complete mixing of algae were 10,2 and 14 d for the submerged cases respectively, which were 8,7 and 6 d shorter than those for the non-submerged cases respectively. Simulated results of different temperature gradients and water depths showed the core algae inhibition zones were larger, and the mixing of algae was quicker, for the submerged case.