The Y-shaped park, spanning almost 50 square kilometers in the countryside of Qingchuan County, is centered on a huge rock erected on the ruins of Donghekou Village and inscribed with "2008--5.12--14:28", the exact date and time of the 8-magnitude quake.
Many landforms resulting from the earthquake can be found in the park, such as landslides, cracks, faults and folds.
Thousands of survivors from Qingchuan and elsewhere attended the opening ceremony on Wednesday morning to pay their respects.
"My mother often wakes up screaming at night, She cannot accept the fact even now," villager Yang Haiqiong said of her mother Jiang Wanqiong. They lost 10 family members in the quake, and only five survived.
Donghekou Village was completely buried under landslides, with more than 780 people dead.
Another huge rock in the park was painted with a red large Chinese character for "xie" (Thanks), and villager He Xianmei was seen cleaning the rock with a white towel on Wednesday morning.
"The xie character expresses our great gratitude to everyone who helped us. No dirt should be seen on it," he said.
"It also tells us survivors to care for each other and live well in the rest of our lives."
The quake centered in Wenchuan County left more than 69,000 people dead, 374,000 injured, 18,000 missing and millions homeless.
More than 31,000 aftershocks have been reported since, with the strongest measuring 6.4 on the Richter scale.
In terms of the intensity and scope of destruction, the May 12 quake is believed to have surpassed the 7.8-magnitude quake in 1976 in Tangshan, northern Hebei Province, which claimed more than 240,000 lives.