He set fire to himself at about 9 a.m., and the flames were put out within 10 seconds, the Hong Kong-based Information Center for Human Rights and Democracy said in a statement.
Guards and an ambulance rushed to the scene and took the man away, the center said, without giving other details, the AP reports.
Beijing police did not respond to telephone and fax requests for information. The administration that oversees Tiananmen Square referred all questions to Beijing's foreign affairs office, which said it had not heard of the case.
Security around the square, historically a gathering place for protests, is usually extremely tight and such incidents are now rare.
In 2003, a laid-off worker set himself on fire, two weeks after another man had set himself ablaze to protest the demolition of his home. Both were hospitalized for injuries.
After it turned out that Deputy Prime Minister Andrei Belousov included the Fonbet betting company in the list of backbone enterprises that can count on state support, everyone started talking about these bookmakers.