This dissertation arose from my puzzle about the origin of the secret memorial system of Qing dynasty. It has been argued that the system was an original creation of Qing dynasty in recent academic circle. Was there any like system in pre-Qing times? There indeed existed like appellations in documents. Were they the same things in nature? The dissertation attempts to answer the question.The secret, palace memorials of Ming, with other names such as secret petitions, secret memorials, secret report, secret exposure, enveloped suggestions, etc., were a special kind of official dispatches to the throne, which were different from common memorials. The secret memorials were transmitted directly to the throne, and were read and commented on by the emperor himself. Therefore they were kept absolutely secret.It's an ancient system that subjects submitted secret petitions to emperor, not a creation of Ming. The first record in documents can be traced back to the reign of emperor Xuan in West Han dynasty. From then on, it was common in ancient Chinese. With political changes in different times, the system appeared in different characteristics. Reversals and repetitions can be found, but the system was improving day by day with strengthening of monarchy. It's a general concept that secret memorials were transmitted directly to the throne, that they were read and commented on by the emperor himself, and that they were kept absolutely secret. In reality, the system was taking shape after a long process of systematization of secret memorial to the throne, which was not emerged suddenly in the early Ming dynasty.The process of systematization was consistent with the development of Ming centralized monarchy. It started from Ming Tai-zu Zhu Yuan-zhang's deprivation of the prime minister's power, then with development of the system of Grand Secretariat, secret memorials to the throne became important measures to consolidate rule of centralized monarchy, and were valued highly by rulers. Emperors from the early Ming to the mid-Ming, many regulations and principles had been issued to systematize secret memorials, which characterized by followings.Firstly, it's about characteristics of the form of secret memorials. There were little differences from that of the common memorials. This was because that the former was greatly influenced by the later. The form of secret memorials was more free and vivacious than that of the common memorials before the reign of emperor Jia-jing. In the early of his reign, emperor Jia-jing made some regulations about the form of secret memorials, formulating the appellation, size, number of lines and words, marks on the cover etc. However, there're no other differences from that of the common memorials.Secondly, it's about ways and channels of transmission and submission of secret memorials. There're four ways by which secret memorials were transmitted and presented to the throne, that is, secret memorials were transmitted by Tong-zheng Si, or submitted directly to eunuchs in Hui-ji Men and then transmitted to the throne, or submitted directly to the throne when going to court, or squeezed into the palace door in emergency, then transmitted by eunuchs to the throne. The later two ways were used only on conditional occasions. The former two ways were common in Ming dynasty. Thirdly, it's about the handling procedure of secret memorials. Contrasted with common memorials, without piaoni(preliminary plan for the emperor's approval) by the Grand Secretariat, or fengbo(covered) by liuke, secret ones were handled directly by the emperor writing comments and signing his name, and directly turning back to those who submitted them, then were put into effect. The handling procedure was simple and direct. Therefore the emperor's power was centralized and strengthened. Fourthly, it's about the qualification for submitting secret memorials. It's important for systematization of secret memorials. Princes and ministers, civil and military officials, even common people were qualified to su