Tone sandhi in Chinese Pinyin refers to the phenomenon that the tone value of some syllables will be affected by the tone behind them when Chinese syllables are issued continuously, thus changing. Also known as tone sandhi, tone sandhi is a method to deal with the merger of words and syllables. Tone sandhi means "merger" in Sanskrit. In all tonal language, the process of tone sandhi is an active action form, but it is also a common tone merging operation form in some aspects.

1, words and characters are connected together, and sometimes words and characters are different when they are said separately, which is called tone sandhi. For example, when two consonants in Putonghua are connected, the first word becomes the upper sound.

2. adjust the tone. In Chinese, the most common tone sandhi rule is that if there is a third tone in a group of two polyphonic syllables, the first syllable in the polyphonic syllables must be raised to the second tone. For example, nǐ h ǐ o (Chinese Pinyin, meaning: Hello) is the most common Chinese greeting. Both nǐ and H ǐ o are the "third tone" in the original tune, but Nǐ, that is, the third syllable, must be upgraded to the "second tone" ní, and "Hello" should be pronounced as ní h ǐ o.