An additive feeding device having a water path, the water path comprising a water supply pipeline, wherein the water supply pipeline is provided with rising convex parts (31, 32) increasing a height of the water path in a fed water stream direction, and wherein on an upstream of the water supply line upstream of the rising convex parts the water supply pipeline is connected with a liquid storage box through a suction structure, the liquid storage box being configured to accommodate an additive, wherein the suction structure is configured to pump the additive into the water supply pipeline to flow to said upstream of the water supply pipeline in a countercurrent mode under a blocking action of the rising convex parts (31, 32); a liquid storage cavity is connected to the water supply pipeline in series, the liquid storage cavity is located on the water supply pipeline on an upstream of a position where the water supply pipeline is connected with the suction structure, and the additive flowing in the countercurrent mode enters the liquid storage cavity to be temporarily stored under an action of the rising convex parts (31, 32), the water supply pipeline comprises a first water supply pipe section and a second water supply pipe section; the liquid storage cavity is connected with a water inlet of the additive feeding device through the first water supply pipe section, and the liquid storage cavity is connected with an opposite-flushing mechanism of the additive feeding device through the second water supply pipe section; and a liquid pumping structure is connected with a middle part of the second water supply pipe section, and each of the upstream and the downstream of a connecting position between the liquid pumping structure and the second water supply pipe section is provided with at least one rising convex part, a first rising convex part on the upstream of the connecting position causes the upstream pipeline to be lower than the connecting position, and a second rising convex part on the downstream of the connecting position causes the downstream pipeline to be higher than the connecting position. the suction structure is configured to pump the additive into the water supply pipeline to flow to said upstream of the water supply pipeline in a countercurrent mode under a blocking action of the rising convex parts (31, 32); a liquid storage cavity is connected to the water supply pipeline in series, the liquid storage cavity is located on the water supply pipeline on an upstream of a position where the water supply pipeline is connected with the suction structure, and the additive flowing in the countercurrent mode enters the liquid storage cavity to be temporarily stored under an action of the rising convex parts (31, 32), the water supply pipeline comprises a first water supply pipe section and a second water supply pipe section; the liquid storage cavity is connected with a water inlet of the additive feeding device through the first water supply pipe section, and the liquid storage cavity is connected with an opposite-flushing mechanism of the additive feeding device through the second water supply pipe section; and a liquid pumping structure is connected with a middle part of the second water supply pipe section, and each of the upstream and the downstream of a connecting position between the liquid pumping structure and the second water supply pipe section is provided with at least one rising convex part, a first rising convex part on the upstream of the connecting position causes the upstream pipeline to be lower than the connecting position, and a second rising convex part on the downstream of the connecting position causes the downstream pipeline to be higher than the connecting position.