This was Williams' 100th US Open victory.
The number 8 seed, Williams, was at her devastating best and dominated Qiang throughout the match.
In the first set, Williams secured a 6-1 victory and in the next set she looked untouchable as she won the set by 6-0.
After the victory, Williams said that this is what she was training for.
"It feels good. It feels like, okay, this is what I've been training for. This is how hard I've been working. It feels like, you know, hard work pays off when that happens," Women's Tennis Association (WTA) quoted Williams as saying.
In the semi-finals, Williams will compete against Elina Svitolina of Ukraine on September 6.