. Its letter form shows the features of the early LI-SHU(the simplified square style of writing Chinese characters). Its 1,309 single letters are classified into five kinds: the independent body letter, the united body letter, the identical form letter, the different stroke letter, the different structure letter. The emergence of the different stroke letter does not make difference in meaning but only in shape. This phenomenon indicates that letters of that age did not fixed forms. The emergence of the different structure letter means that the increase, ommission, interchange of the Radical were misunderstood as completely different letters. The form-signs, added to the radical, were merely no more than a decorative function, because the primary letter had a complete meaning. The addition of the meaning signs strengthened the original meaning of the primary letter. The addition of the sound-sign to the Radical signals the sound of the letter or reinforced the role of the sound-formation letter. The interchanges of the Radical consist of the interchanges of form-signs, meaning-signs, and sound-signs. Interchanges between completely different letters in structure as well occurred. In addition, some irregularity and adjacency of letters mistakenly caused interchanges. This emergence of the different structrue letters was a general linguistic phenomenon of the All-Nation Period. However, the rarity of the identical form letter shows that it had already reached the mature stage of the letter development.