With the help of semantic processing of keyword in semantic retrieval technology, a mobile terminal-oriented text to speech system was designed for agriculture knowledge. The ambiguous phrase encountered in text segmentation were cutting by using semantic search technology which could converted agricultural text knowledge to smooth and natural voice, and popularized agricultural knowledge combining call center and mobile terminal technology. Firstly, the text analysis flow was analyzed, and the ambiguous phrase which was the key point of text to speech processing was confirmed. Based on this key point, the word segmentation dictionary was designed, and the ambiguous phrase was extracted based on the dictionary matching and statistical analysis. Secondly, the ambiguous phrase was processed based on semantic retrieval and the segmentation of ambiguous phrase was realized. Finally, the functions of speech synthesis and prosodic processing were realized with the software of Cool Edit Pro 2.0, and mobile terminal-oriented text to speech system was developed for agriculture knowledge which could effectively solve the problem of ambiguous phrase processing.