Hu's participation underlines the importance the country places on the Olympics and its hopes to display a confident, strong China to the world when the games open Aug. 8.
The ceremony 130 days before the start of the Olympics was broadcast on state television, and comes a week after the lighting ceremony for the Olympic torch in Greece was marred by protests.
The torch relay has been heavily promoted by the Chinese government. A chartered Air China plane carrying the Olympic flame from Greece was greeted at the Beijing airport by hundreds of schoolchildren waving Chinese and Olympics flags.
Chief Beijing organizer Liu Qi carried the flame off the plane in a small lantern. He was greeted by Zhou Yongkang. A former public security minister, Zhou is a member of the Communist Party's supreme nine-man Politburo Standing Committee.
About 5,000 people, including 220 foreign journalists, were on hand for the ceremony in the middle of the vast square in the heart of Beijing. There seemed to be few ordinary citizens present, with most attendees drawn from the ranks of officials, entertainers and large numbers of middle-aged women carrying out orchestrated cheering.
All the seats were a bright red and faced north where a huge portrait of Mao Zedong overlooks the square. Martial artists and dancers wearing costumes representing minority ethnic groups, including Tibetans, cavorted on a huge red carpet covering much of the north end of the square.
Hein Verbruggen, who heads the International Olympic Committee's commission monitoring the organization of the Beijing Olympics, was also at the ceremony.
"All along the relay route people will be touched by the Olympic Games and what it means," Verbruggen said.
Authorities have noticeably boosted security in downtown Beijing in recent days. Two subway stations at Tiananmen Square was closed and dozens of police were at other subway stops. Police also closed the square to vehicles, and pedestrians and bicyclists were kept at one block away.
Concern about anti-government protests extended to the state television broadcast. Although the broadcast signal carried a banner saying it was "live," there appeared to be a delay of about 1 minute.
Last week, the China Central Television broadcast cut away from the flame lighting ceremony in Greece when protesters ran behind Liu Qi as he gave a speech. It showed stock footage of the ceremony site instead.
After a one-day stop in Beijing the flame goes Tuesday to Almaty, Kazakhstan, the start of a monthlong 20-country, 85,100-mile global journey.
The grandiose relay is the longest in Olympic history and has the most torchbearers - a sign of the vast attention lavished on the Games by Beijing, which hopes to use it to showcase China's rising economic and political power.
Instead, however, it has provided a stage for human rights activists who have been criticizing China over a range of issues including its handling of Muslims in the far west of the country, its control over Tibet and its relationship with Sudan.
Tibetan and rights groups have said they will stage protests along the torch route. That includes stops in London, Paris and San Francisco over the next 10 days.
The relay has especially focused attention on recent unrest in Tibet, the worst in the Chinese-controlled region since 1989.