The vowel /(vee with swirl)/ in Mandarin has traditionally been documented as a simple vowel although it has been noticed to involve more complicated articulator movements in its production than a monophthong. Three male speakers of Beijing Mandarin were recorded for an acoustic study of this vowel. The frequency and energy values of F1 through F4 of the beginning part (around 20 ms), the first quarter, and the rest of the vowel were measured from the spectrogram and LPC using CSL. Results of two-tail paired t tests show that the first quarter of the vowel has significantly weaker energy in F2 through F4 than the rest of the vowel at p=0.05 level, indicating approximantlike properties in this part. Also, the initial 20 ms of the vowel has higher F1 and lower F2 than the following part, indicating a possible pharyngeal constriction. So phonetically, /(vee with swirl)/ consists of a very short pharyngeal approximant [(backward glottal stop)], a velar approximant [(inverted em)|], and a real vowel [(vee with swirl)] in sequence. This phonetic characteristic accounts for the fact that glottal stop insertion before a syllable-initial /(vee with swirl)/ is much less likely than that before a real onsetless monophthong /a/, but patterns with that before a syllable-initial /w[inf o]/.