This paper examines the tonal aspects on code-switching among Chinese-Australian bilingual children. Fifteen boys and fifteen girls aged from six to ten were chosen from three different primary schools in Victoria. Chinese is a tone language with a very highly constrained syllable structure. Mandarin Chinese has four basic tones with an additional neutral tone. The Chinese fourth falling tone corresponds to English intonation. A Chinese third curve tone, when immediately followed by a first, second, or fourth tone or most neutral tones, usually becomes a half third tone, that is, the tone that only falls but does not rise. In addition, both the neutral tone words and the words with a weak stress are pronounced in a falling tone, the same as English. When the switches to English occur, they are usually following the Chinese fourth, half third and neutral falling tones or weak stress of word. These fading tones may also facilitate transitions between Chinese and English.