Li Runsen, the powerful technology director of China's ministry of public security, is best known for leading Project Golden Shield, China's intensive effort to strengthen police control over the Internet. But last month Mr. Li took an additional title: director for China Security and Surveillance Technology, a fast-growing company that installs and sometimes operates surveillance systems for Chinese police agencies, jails and banks, among other customers. The company has just been approved for a listing on the New York Stock Exchange. The company's listing and Mr. Li's membership on its board are just the latest signs of ever-closer ties among Wall Street, surveillance companies and the Chinese government's security apparatus. Wall Street analysts now follow the growth of companies that install surveillance systems providing Chinese police stations with 24-hour video feeds from nearby Internet cafes. Hedge fund money from the United States has paid for the development of not just better video cameras, but face-recognition software and even newer behavior-recognition software designed to spot the beginnings of a street protest and notify police. Executives of Chinese surveillance companies say they are helping their government reduce street crime, preserve social stability and prevent terrorism. They note that London has a more sophisticated surveillance system, although the Chinese system will soon be far more extensive. Wall Street executives also defend the industry as necessary to keep the peace at a time of rapid change in China. They point out that New York has begun experimenting with surveillance cameras in Lower Manhattan and other areas of the city.