The two-time Grand Slam champion from Spain had 13 aces, including seven in the final set.
"I was expecting a very tough match, and at the end, it was," Muguruza said. "I think she came out in the second set playing much better. I just kept competing and I'm happy with these kind of victories."
Muguruza will next face Ekaterina Alexandrova after the fifth-seeded Russian defeated fourth-seeded Qiang Wang 3-6, 6-4, 6-3.
Also, Elena Rybakina upset third-seeded Elise Mertens 6-4, 4-6, 6-2. She will next meet Kristyna Pliskova, who beat Kateryna Bondarenko 6-4, 6-4.