Wang came into the match having recorded impressive wins over Timea Bacsinszky, Elise Mertens and Kristina Mladenovic, but made far too many unforced errors.
Although Halep's own performance was far from faultless, particularly in the first set, the Romanian triumphed 7-5 6-1 and will now face Petra Martic in the last eight.
If Wang was high on confidence following her performances earlier in the tournament, her morale was surely raised further as she twice responded immediately to falling a break down in set one.
However, after receiving a pep talk from coach Darren Cahill at a change of ends, Halep raised her level to reel off three successive games and take the opener 7-5, although she was forced to save a break point before wrapping up the set at the fourth attempt with an unreturned serve.
The writing was on the wall for Wang when she also lost the first three games of set two.
Although the Chinese eventually stopped the rot with a break of her own, Halep soon took charge again and cruised to an ultimately routine victory.