Rhythm plays an important role in the naturalness of speech. This study compared rhythmic patterns of Mandarin speech between native speakers and two groups of L2 speakers whose first languages were Cantonese and English, respectively. The study started from isolated words, but focused on continuous speech, for which eleven durational metrics were used as objective rhythm indicators. The results on continuous speech showed that nonnative Mandarin gave a quite similar rhythmic mode as native one in terms of rate-normalized/independent metrics, but shifted towards the stress-timed class in terms of raw metrics, regardless of the rhythmic class of the L1. This seems to conflict with the L1 transfer effect and the results for isolated words, but it coincides with auditory impression and can be explained by speech rate difference and the lengthening effects associated with the change in prosodic structure.