This paper presents an aerodynamic analysis of intonation on reading speech in Hong Kong Cantonese. In this study, the variation in oral airflow rate, fundamental frequency (F0), as well as intensity level of the acoustic signal is studied. The goals of this study are to evaluate the correlations among fundamental frequency of vibration of the vocal folds, rate of oral airflow and intensity level, and to search for (if any) the domain of the ‘basic breath unit’ within paragraph. The data were collected and analyzed on three subjects who are native speakers of Cantonese. The results suggest first that in spontaneous speech, the variation in oral airflow rate may be used to facilitate some changes in F0 contour, whereas the correlation between the variation in intensity level and F0 changes is not significant in this study, and second the ‘basic breath unit’ at paragraph level does not necessarily match the domain of syntactic units, mainly clauses or sentences, and unfilled pause. The frequency of the occurrences of ‘basic breath unit’ within paragra ph varies across speakers. Such interspeaker differences may due to the differences in speaking style and basic physical need among speakers.