The Simplification of Chinese initials is a salient change from the middle ancient times to the recent antiquity, which mostly caused by the devoicing of the fully voiced initials. Although the devoicing of the fully voiced initials has a universal law, yet this devoicing has no influence over the semi-voiced initials. Through the theory of markedness and the theory of distinctive feature, we can find that the fully voiced initials are obstruents, but the semi-voiced initials are sonorants. The devoicing involves only [＋voice] of the obstruents, not the [＋ voice] of the sonorants, which reflects the change from the marked to the unmarked.