There exist new words and error words in Chinese information of web pages. In this paper, we introduce our definition of semantic similarity between sememes and their theorems. On the base of proving the theorems, the influence of the parameter is analyzed. Moreover, this paper presents a novel definition of the word similarity based on the sememe similarity, which can be used to match the new Chinese words with the existing Chinese words and match the error Chinese words with correct Chinese words. And also, based on the novel word similarity, a matching method of information segments is pres...