Objective: This study aimed to explore the appropriate cooking method of chestnut. Methods: Nine kinds of thermal treatment on the quality of chestnut were compared. The thermal treatment included chestnut fruit (roasting, cooking without water under normal-pressure, cooking within water under normal-pressure, cooking without water under high-pressure, cooking within water under high-pressure) and chestnut kernel (cooking without water under normal-pressure, cooking within water under normal-pressure, cooking without water under high-pressure, cooking within water under high-pressure). Results: The content of starch and polyphenols in chestnut were decreased by the nine kinds of thermal treatment, while the amylose content increased. Compared with the shelling method, the ripening method of chestnut with shell was a more effective processing to retain polyphenols. The content of soluble sugar in chestnut fruit by cooking without water under normal-pressure was the highest (125.187 μg/mg), and the sweetness value was the highest (121.53), with the highest SRC score of 71.97. The moisture content of roasted chestnut fruit was the lowest (36.69%), and the hardness was the highest (8.9 N), with the lowest texture score of 2.02. Conclusion: The chestnut fruit by cooking without water under normal-pressure can be used as a suitable processing method to be eaten.