The invention discloses a method for smelting ultra-low carbon steel by low oxygen site in the whole process. The ultra-low carbon steel comprises the chemical components of, by mass, no more than 0.0030% of C, 0.01% of Si, 0.08-0.18% of Mn, no more than 0.015% of P, no more than 0.010% of S and 0.015-0.055% of Al<sol>. The process of KR stirring desulfuration, a top-bottom combined blown converter, an RH vacuum refining furnace and a slab continuous casting machine is adopted for smelting production. According to the method, the mode of converter terminal low-oxygen and slag modification lowtotal iron, RH furnace low oxygen site deep decarbonization, continuous casting machine fully-protected argon sealing and tundish breathable block brick argon blowing is adopted, the total iron is controlled within 5% after slag modification, end-point oxygen after RH furnace deep decarbonization is controlled to be about 350 ppm, casting blank oxygen is controlled within 20 ppm, the zero-order ratio of inclusions reaches 97% or above, RH end-point carbon is controlled within 20 ppm, and the casting sequence of the continuous casting machine reaches 10 times. The castability and casting blankquality of ultra-low carbon steel such as DDQ-grade cold rolled steel are improved, the number of inclusions in the steel and the shape control level of the steel are improved, and the percent of passof steel blanks is effectively improved.