ITV News Asia Correspondent Debi Edward attended the ceremony to mark 100 years of the Communist Party of China.
A huge audience of 70,000 spectators gathered in Beijing's Tian'anmen Square for centenary celebrations - with others watching on televisions up and down the country.
In a long speech on the future of the party, China's leader pledged to use "history as a mirror" and said the country would focus on "creating a brighter future".
A crowd of 70,000 gathered in Tian'anmen Square for Xi Jinping's speech
Xi Jinping said China will not allow itself to be bullied and those who try face "broken heads and bloodshed in front of the iron Great Wall of the 1.4 billion Chinese people".
Wearing a grey buttoned-up suit of the type worn by Mao Zedong, Xi Jinping spoke from the balcony of Tian'anmen Gate.
He received raucous applause when he described the CCP as the force that had restored China's dignity after taking power amid civil war in 1949.
"The Chinese people are a people with a strong since of pride and self-confidence,” the party leader said.
"We have never bullied, oppressed or enslaved the people of another nation, not in the past, during the present or in the future."
The ceremony was broadcast on big screens around Beijing and other majors cities.
Crowds watched a gun salute and guard of honour
Xi Jinping continued: "At the same time, the Chinese people will absolutely not allow any foreign force to bully, oppress or enslave us and anyone who attempts to do so will face broken heads and bloodshed in front of the iron Great Wall of the 1.4 billion Chinese people,
He did not say what those forces were, but China is enmeshed in a deepening rivalry with the US for global power status and has clashed with India along their disputed border.
China staged an aerobatics performance over Tian'anmen Square
Military aircraft in formation flew over the square during the ceremony.
A 100-gun salute was also fired, and the guard of honour marched through the square, holding the national flag.
Armed helicopters flew in a formation to spell out "100" in the air, and fighter jets formed the numbers seven and one - the CPC's 100th founding anniversary falls on July 1 this year.
The centenary coincides with the 24th anniversary of Hong Kong's return to Chinese control.
The occasion is usually marked by protests in the former British Colony, but a strict national security law imposed in Hong Kong by China has been authorities crackdown on dissent and protest.