As a new branch of location-based query, space keyword query has gained extensive attention from researchers and become a new hotspot of database filed. Able to comprehensively consider the distance between query object and query point as well as similarity degree of keywords, such query can better satisfy specific requirements of location-based services. In this paper, a space keyword index structure is designed, so as to effectively organize keyword information, location information and index information of objects on various sides in road network. Besides, keyword k-nearest neighbor query of road network under wireless broadcast environment is proposed. Finally, performance of the proposed index structure and algorithm is verified through simulation experiment.