The characteristics of multiple pattern matching in mixed Chinese and English text and the problem of the existing multiple pattern matching algorithms used for processing mixed Chinese and English text are analyzed. A theorem of multiple pattern matching in mixed Chinese and English text is discovered and proved. A novel multiple pattern matching algorithm based on the threaded trie tree is proposed, which expands the standard trie structure, constructs the hash trie matching machine with the codes of Chinese and English characters, and threads the trie tree according to the characteristic of patterns set. The proposed algorithm does not need complex hash operation, and the matching pointer does not need backdate during matching. Theoretic analysis and experimental results demonstrate that the proposed algorithm efficiently solves the space expansion problem, and process mixed Chinese and English text correctly and efficiently with lower time and space complexity.