The invention provides a children swimming teaching system which comprises a buoyancy collar sleeving the neck and buoyancy ankle rings sleeving the left ankle and the right ankle. The buoyancy ankle rings is formed by air bags, and each air bag is connected to a holdable rubble ball which is in full shape under the natural state through a soft tube; when the rubber balls are in full shape, the buoyancy ankle rings are in soft flat state, and the maximum buoyancy at the buoyancy rings is not enough to float legs of children; when the rubber balls are pinched flat, air in the rubber balls is pressed into the buoyancy ankle rings, the buoyancy ankle rings are in full shape, and the maximum buoyancy at the buoyancy ankle rings enable the legs of the children to float up. By the arrangement, the children can be assisted in alternative water-repelling movement training with both legs lightheartedly, water-repelling resistance can be greatly reduced, and meanwhile, difficulty in training of adults and the children can be reduced at the same time.