The tournament is Henin's first grass-court appearance in about three years and she hasn't lost a set this week.
She defeated Kristina Barrios 7-5, 6-3, closing the match with a service break at love. It was her fourth break of the match. She suffered a break herself in the first set but dominated the second, losing only five points in four service games.
Henin next draws fifth-seeded Alexandra Dulgheru, who got by No. 4-seeded Yaroslava Shvedova 6-3, 3-6, 6-4 in her quarterfinal.
The other semifinal will send seventh-seeded Andrea Petkovic against Kirsten Flipkens.
Petkovic advanced with a 6-2, 7-6 (7-5) win over Sandra Zahlavova in which Petkovic had 10 aces. Flipkens was a 6-2, 6-3 winner over Dominika Cibulkova, firing eight aces and dropping serve just once.