Pedestrian navigation system has been widely used in many fields. In order to offer navigation information intelligible for pedestrian, we provide navigation sentences to users, which can be easily displayed on cellular phones with small display area. In addition, the navigation sentences can be converted into voice, which is useful for users in some special situations or with visually impairment. Navigation sentences can separately help pedestrians to go to the destination, or can be combined with electronic map to provide more intuitive navigation information. Compared with guidance maps, navigation sentences are easy to transmit and manage. The navigation sentences are described by XML (eXtensible Markup Language) and can be created on the server automatically based on the users' position and destination. This paper will discuss the structure of the pedestrian navigation system using navigation sentences. The structure and generating process of navigation sentences are also described.