The invention and use of flat pot is a great achievement in the history of leaky pot development. Since the Song Dynasty, flat pots have been widely used in leaky pots, and even developed into second-class flat pots, further improving their stability. In the Jiaotai Hall of the Forbidden City in Beijing, a set of nine-year-old broken kettle wine is completely preserved. It adopts the first-class compensation kettle and the first-class flat kettle, and combines the two ways of ancient kettle breaking technology to complete the timing task in the palace.