The utility model relates to an anti-leakage water-saving flush tank. The existing flush tank has the disadvantages of easy leak, large maintenance quantity, and water resource wasting. The utility model is characterized in that the upper part of the inner side of an outer barrel is provided with an inner barrel through a shaft, the barycenter of the inner barrel is positioned below the shaft, and the inner barrel can be rotated around the shaft. The lower part of the inner side of the outer barrel is provided with a siphon pipe whose one end is extended from the bottom part of the outer barrel. The utility model is suitable for flushing the filth between gaps in a latrine.