Secret memorials to the throne were confidential documents submitted by Ming courtiers to the emperor. Compared with normal memorials to the throne, secret ones have quite some unique characters, and its special composing format is undoubtedly the most distinct one. Moreover, the form of this particular format also indicates that the use of secret memorials to the throne has already been initiatively institutionalized. Generally speaking, the composing format of secret memorial to the throne in the Ming Dynasty has undergone the following two different phases: At the early and medium term of the Ming Dynasty, the composing format had hardly any obvious difference from the common ones. While, at the early stage of emperor Jia-jing, the composing format, which imposed great influence on the later regimes, has finally been shaped. The composing format of secret memorials to the throne includes three major parts: opening, statement and closing. Furthermore, the secret memorial to the throne also has more taboos than the common ones. So to say, it is just because the above-mentioned characters that distinguished secret memorials to the throne from other kinds of documents.