The US athlete is the No. 2 ranked player in the tournament.
Defending champion Coco Gauff defeated Eva Leys in two sets to claim a spot in her third successive Beijing competition semi-final.
The third-ranked player took one hour and 28 minutes to beat her opponent from Germany with a 6-3, 6-4 result.
The American, a two-time Grand Slam winner, broke Leys on three occasions in the first set, successfully taking three out of four chances to break.
"I'm satisfied with how I played - she's a tough opponent and she hit some amazing strokes on the run, but I gave my all to be assertive and good tennis," commented the champion.
"I think maintaining belief in my game proved crucial. Avoiding being overly defensive when I was ahead, I made a single defensive play in the last game but following that I played good tennis."
Gauff, who has struggled with her serve at points this season, recorded an impressive 79% success rate on first serves during the contest.
The 21-year-old, who was knocked out in the opening round of the Championships after winning the Roland-Garros earlier this year, is now the highest-ranked player left in the tournament.
She will meet either Amanda Anisimova or Paolini in the final four.
