The invention discloses a production process of high-quality ultra-low-carbon IF steel. The production process includes the procedures of blast furnace molten iron, DeS pretreatment desulfurization, DeP dephosphorization, DeC decarbonization, RH vacuum treatment and CC conventional slab continuous casting. In the DeP dephosphorization procedure, the final temperature is not lower than 1330 DEG C, and the mass percent of final semi-steel components are controlled so that the mass percent of C can range from 3.40% to 3.60%, the mass percent of S cannot be higher than 0.010% and the mass percent of P cannot be higher than 0.040%. In the DeC decarbonization procedure, non-turning-down direct discharge is adopted, and the mass percent of final molten steel components are controlled so that the mass percent of C can range from 0.025% to 0.040%, the mass percent of S cannot be larger than 0.011% and the mass percent of P cannot be larger than 0.010%, and the final temperature ranges from 1680 DEG C to 1700 DEG C. In the RH vacuum treatment procedure, a vacuum mechanical pump is used for adjusting the vacuum degree. In the CC conventional slab continuous casting procedure, a tundish is made of non-carbon and non-magnesium refractory, and the draw speed is controlled to range from 1.1 m/min to 1.4 m/min. By means of the method, a continuous casting billet without any defect is produced, high-quality hot-rolled coiled plates are produced through hot rolling, and high-quality continuously-annealed and zinc-plated products are finally produced through cold rolling.