The number four seed showed toughness overcoming a thigh injury to beat Li in three sets to reach the last four at the All England Club for the second year in a row.
"I'm very happy to have got through, and even when I was struggling a little bit in the third set," she told BBC Sport. "I'm very, very happy to be in the semi-finals."
She added on her injury: "Too much tennis the last few days, that's why I was struggling with that, but I think it's a good problem to have. I'm just going to keep going and try my best in the semi-finals."
The 24-year-old will now face Sabine Lisicki in the last four.