However, he invested all his earnings in a failed business project in 1992, resulting in the closure of his factory. "We wanted to export dried apricots to Japan, but they terminated the contract," he said.

Liu said the failure of his business was partly due to his lack of education. While toiling as a migrant worker in Beijing in the following years, Liu studied textbooks from both Peking University and the Renmin University of China that he purchased online.

In 2001, China eliminated the age limit for the gaokao.

A record 10.5 million people sat for the exams in 2008. In summer 2017, the story of a senior in his 80s taking the test inspired Liu and reminded him of his aspirations decades ago.

Since then, Liu has taken the gaokao four times.

"My niece was a postgraduate student at Nanjing University in Jiangsu province. She sent me lots of learning material and helped me with the preparation," Liu said.

Inspired by the composition portion of the gaokao, Liu wrote a letter to his younger self.

"I really want to help you experience the good living conditions and educational opportunities in your rural area that I'm enjoying now. It is a pity that now I can no longer hold a shovel to help build things in the village, but I still haven't given up. I am taking part in the exams again."

Liu said he hopes his achievement will motivate younger generations.

"I'm willing to be a role model for youngsters," he said. "They are expected to cherish the environment and be brave in the face of adversity."

He realized his dream last year when he scored 245 points on the exam. That fact that his score wasn't as high as others didn't deter him from starting a new chapter in his life.

"Now, I am satisfied with life in college. Classmates often lend me a hand when I have trouble and have taught me how to live more conveniently with a smartphone," he said.

"Walking around the campus with young students who are vigorous and energetic makes me feel like I am 20 years younger."

Liu hopes to apply for a master's degree in law after he graduates, and maybe write books about political economy in his spare time.

"Some villagers worked for a whole year to earn 10,000 yuan ($1,563), which is not even enough for them to call a lawyer to resolve disputes. I want to help villagers in my hometown by providing them with legal knowledge and services," he said.