Keyword search is the primary way for ordinary users to access the Web content. It is essentially a syntax match between users’ key-ins and the index structure of information systems with a relevance-ranking way to sort the hitted documents. The syntax match can rarely satisfy users’ information need when the keywords and index are not syntically similar while share a lot semantically. This paper proposed a way of semantic keyword expansion with a re-ranking to handle this problem. Experimental results show that our method helps in improving the quality of keyword search and particularly in the cases of keywords with widely-used synonyms or parasynonyms.