One of the key issues in spoken language translation is how to deal with unrestricted expressions in spontaneous utterances. This research is centered on the development of a Chinese paraphraser that automatically paraphrases utterances prior to transfer in Chinese-Japanese spoken language translation. In this paper, a pattern-based approach to paraphrasing is proposed for which only morphological analysis is required. In addition, a pattern construction method is described through which paraphrasing patterns can be efficiently learned from a paraphrase corpus and human experience. Using the implemented paraphraser and the obtained patterns, a paraphrasing experiment was conducted and the results were evaluated.