Berdych, the top seed, defeated number three seed Robredo 6-1, 6-4 to advance to the final.
He will face Guillermo Garcia-Lopez, also of Spain, as the number four seed upset Marin Cilic of Croatia, seeded second and the winner of last year's US Open, 1-6, 7-5, 6-3.
The semi-final matches were scheduled to be played on Saturday but were delayed and finally postponed after persistent rain fell over the southern Chinese city.
Both matches Sunday also suffered delays after play began.
Berdych and Garcia-Lopez are scheduled to play for the championship on Monday.