Through the combination of acoustic analysis of speech and dynamic palatogram, researches are done on phonetic properties of /y, w, yu/ as initials and /i, u, v/ as main vowels and transition vowels. This paper points out /y, w, yu/ as initials are of properties of semivowels; while /i, u, v/ as transition vowels still stick to properties of vowels, though they change more quickly and therefore can be called glides.