The demand for communications anywhere, anytime, and on any device without recording the date is growing with the development of modern information technologies. Current wireless communications enable people to freely exchange information, while web services provide loosely-coupled, language-neutral, and platform-independent ways of linking applications within organizations, across enterprises, and across the Internet. This paper describes a mobile information system for police service, which integrates wireless communication technologies and web service technologies. The system satisfies the special demands of police information systems, such as security and interoperability. Policemen in the system can use various kinds of mobile terminals, such as mobile phones, tablet PCs, personal digital assistants, and laptops equipped with wireless LAN or GPRS to access data in the central database. The system is based on web services with a secure web service architecture and simple object access protocol message passing.