Abstract: According to the relations between frequencies and amplitudes in a group of three harmonics in a spectrogram, the frequency, amplitude, and bandwidth of the formants can be determined. This paper suggests simple equations by which the formant data can be easily calculated from measured materials. Discrimination of different patterns of Single- and Double-Formant Structures are also discussed. With this treatment, formant data of the vowels and voiced consonants of Standard Colloquial Chinese （Putonghua） are given.