The poison that Qin Qingwu used was imported from The Stars and Stripes Country, and once inflicted by it, one would remain unconscious forever, unless you had the Antidote.
Before, Qin Qingwu personally witnessed Ding Fan drinking the soup laced with poison. Qin Qingwu knew too well how formidable Ding Fan was, having previously dispatched members of the Restoration Organization to assassinate Qin Manshu, only for Ding Fan to unexpectedly intervene and later rescue Manshu.
It was precisely because he knew of Ding Fan's capabilities that Qin Qingwu planned to use poison against them.
Yet, even though Ding Fan had obviously been poisoned, he now stood up, which was nothing short of miraculous.
Keep in mind, that poison was colorless and tasteless, with potent effects, and Qin Qingwu had it specially acquired from the black market in The Stars and Stripes Country. And despite such a formidable poison, Ding Fan was still able to stand up.