Sun Zhanyuan was born in a poor family in Linzhou City, central China's Henan Province in 1925. His parents died when he was in his tender age. In 1946, Sun Zhanyuan joined the Chinese People’s Liberation Army and in the War of Liberation (1945-1949), he fought dauntlessly in the combats and made meritorious services, and became a member of the Chinese Communist Party in 1948. In March of 1951, he joined the Chinese People’s Volunteers and went to the War to Resist U.S. Aggression and Aid Korea.

On October 14, 1952, when the Battle of Shangganling　broke out, Sun Zhanyuan, as a platoon leader, led all the soldiers of the platoon to perform assault operations at the main position of No. 597.9 Highland. In the fierce combat, his legs were seriously injured due to the enemy's bombing, but he refused to be evacuated from the battlefield. He told his men, “I am commander of the platoon, I will never leave the frontline before completing the task.”

He crawled in the trench while giving combat order to his men. Under his cover with two machine guns, Yi Caixue, a soldier in his platoon, blew up the enemy’s last three bunkers. At the same time, he killed more than 80 enemies.

When the enemies swarmed into the position again, Sun Zhanyuan did not hesitate to roll into the enemy group along the hillside, and detonated the last grenade, died together with eight enemy soldiers.

After the battle, Sun Zhanyuan was posthumously awarded the Special-Class Merit and the honorary title of "First-Class Combat Hero" by the CPV Headquarters. The Standing Committee of the Supreme People's Assembly of the Democratic People's Republic of Korea posthumously awarded him the honorary title of "Hero of the Democratic People's Republic of Korea".