The invention relates to a search term recommendation method and system based on a multi-branch tree. The method comprise that steps that: A, a multi-branch tree term chain data generation process: splitting each hot term into a plurality of independent words, generating a term chain according to the sequence of the words from first to last in the hot term, each word is a node in the term chain, and nodes corresponding to the same word in different term chains are used as public nodes to generate multi-branch tree term chain data; B, a search term recommendation process: searching multi-branch tree term chain data accord to that currently input terms, taking a term chain that matches the inputted words as a recommended term.