Firstly, wash the chestnuts with clean water, rinse off impurities, then classify the chestnuts according to their size and process them separately. The cooking recipe is composed of 80g star anise, 50g cinnamon, 15g cloves, 15g Chinese prickly ash, 20g licorice, 400g salt, 250g sugar, and 10kg water. The outer skin of chestnut fruit is leathery, thus it is generally difficult to absorb flavor when boiled or soaked. A simple vacuum infiltration method can be used. The seasoning materials is boiled for 30 minutes according to the recipe to make them become a seasoning liquid, and then put the chestnut fruit into the seasoning liquid to cook.