Trump fell 5-3 to Vafaei in Beijing, with the Iranian set to face Mark Williams for a place in the final.
Vafaei made two centuries on his way to victory, with breaks of 100 and 106 coming before the 22-year-old bested Trump in a safety exchange to win the match in the eight frame.
Meanwhile, Williams dispatched Shaun Murphy 5-1 in an edgy encounter which saw the two-time world champion win five straight frames despite recording just the one notable break of 52.
Elsewhere, Mark Selby ousted Stephen Maguire 5-1 to set up a semi-final with Wilson, who beat Ding Junhui by the same score.
Selby coasted for much of the quarter-final and finished with runs of 76 and 72 in frames five and six.
Read the full article on eurosport.co.uk: Trump crashes out of China Open quarters