Phrase-final lengthening is a phonetic fine-tuning phenomenon related to boundaries, but it is also language specific. The present study explored the influence of tones on the final lengthening effect in Mandarin and compared the final lengthening effect with the same phenomenon in English. The results showed that the rank of the tones is tone 3 > tone 2 > tone 1 > tone 4 in Mandarin. Final lengthening also gets stronger as the prosodic level of the boundary gets higher except when the final word is tone 4 in which IP-UF and IP-F does not show a significant difference. Tones can influence final lengthening especially tone 3, and this is attributed to tone 3’s contour. In general, Mandarin and English are similar in boundary effects (IP-UF > IP-F > ip). However, in English final lengthening can also influence the stressed syllable, but final lengthening in Mandarin only influences the vowel of the final syllable.