The research of metaphor is an increasing important field in cognitive science. Metaphors influence our life as a kind of thinking. They involve the comparison of target and source situations. In this paper, we concern mainly with linguistic metaphors and highlight the cognitive meaning of metaphors. First, we will put forward the grammar of Chinese metaphors. Our syntactical rules will handle the grammatical forms of metaphors we intend to generate and interpret. Then the constraints for Chinese metaphors generation are proposed. According to the grammar and the constraints, we construct a system of Chinese metaphor generation.