The anniversary was marked by a one-minute silence
Chinese President Hu Jintao has led the commemorations to mark the first anniversary of the Sichuan earthquake.
Mr Hu was joined by other officials at a memorial ceremony held in Yingxiu, the epicentre of the earthquake.
In a speech at the event, the president said Chinese people had "written a great chapter" with their rescue and reconstruction work.
People across the earthquake-hit areas held their own private ceremonies to mark the loss of loved ones.
Mourners visited ruins and graves, lighting incense to comfort the dead.
The earthquake, which struck Sichuan province on 12 May last year, left nearly 90,000 dead or missing.
On the eve of the anniversary, President Hu said the disaster had galvanised the Chinese nation.
"Confronted with this immense disaster, the masses of Chinese people and military were as one, forming a fortress of unified resolve," Mr Hu said, according to the state-run Xinhua news agency.
It was a theme he returned to in his speech at the memorial ceremony.
"We are going to win an all-out victory in our post-earthquake construction efforts," he told assembled officials, who included China's Vice-Premier Li Keqiang.
President Hu said the earthquake reconstruction would be completed one year ahead of schedule - by September next year.
He added: "People in disaster-hit areas have been going back to their normal lives."
Time to remember
The ceremony, held among the ruins of the Yingxiu, was broadcast live across China.
It began when wreaths were laid at a sculpture of a clock - whose hands were set at 14:28, the exact time the earthquake struck.
President Hu, head bowed, then stood in silence to honour the dead.
Other, less formal, ceremonies to mark the occasion were held in other towns and villages in the earthquake-hit areas.
Both locals and tourists visited Beichuan, a town that was completely wiped out by the earthquake and is usually barred to the public.
They lit candles and incense, as well as ritual paper money, to remember their loved ones who died when the entire town was destroyed.
"I feel the earthquake isn't over yet. Every time I see something about it, I feel like crying," Zhou Ya, a 20-year-old woman who lost several family members in Beichuan, told reporters.
China has been widely praised for its rapid response to the Sichuan quake.
But many questions have been left unanswered.
The government promised a full investigation into why so many schools collapsed during the earthquake, but none had yet been published.
And parents who believed the schools had been shoddily built have been harassed for campaigning to get officials to look into the issue.
Chen Jigang told the BBC: "We still don't get an answer and we can do nothing about it. Our daughter was almost 18 years old when she was killed in the quake.
"We have prayed for her to have a better life in the other world."
Another grieving parent, An Ping, told the BBC's Chinese service that she had visited the ruins of the school where her only child had died.
"When the quake happened, my daughter was trapped underneath the rubble. She wasn't injured but she eventually died as no-one came to rescue her.
"Now, my child has been dead for a year. When our daughter was born, we expected her to grow up and bring us happiness. Now all our hope is gone."
Even on the day of the anniversary, one parent told the BBC that he was being watched by police.