As two men walked by an apartment complex, they noticed the child on a window ledge four stories up.
The one-year-old teetered on the edge, and then fell.
Both men are seen raising their arms as they move, trying to judge where the boy was falling.
Jumping a step forward at the last second, one of the men cradled the child safely into his arms.
"I didn´t think too much at the time. I was just afraid of failing to catch him," one of the men identified only as Li, told a Guangdong, China TV station.
Millions have seen, and commented on the video via YouTube. "Wow, that is what I call nice catch! That guy is a hero!" one wrote.