The invention discloses a converter smelting and external refining control method of HIC (Hydrogen Induced Crack)/SSCC (Sulfide Stress Corrosion Cracking)-preventing steel. A smelting process route of converter-CAS (Control Automatic System) station-LF (Low Frequency) refining-VD (Vacuum Distillation)/RH (Relative Humidity) vacuum-calcium treatment-soft blowing-continuous casting is adopted. Low-phosphor requirements of the HIC/SSCC-preventing steel are obtained through controlling the converter smelting process route; and meanwhile, part of deoxidation type inclusions are removed by carrying out strong deoxidation, alloying as well as residue washing in a converter steel-tapping process, and over 60% of sulfur in molten steel is removed by sufficient stirring of the residue washing. In the LF refining process, refining furnace slag which is high in alkalinity, high in Al2O3 and strong in reducibility is obtained by regulating components of the refining furnace slag, and the inclusions are transformed and removed towards a low melting point by virtue of balance of the furnace slag-molten steel-inclusions. Proper vacuum treatment time and vacuum degree are kept at a vacuum treatment furnace so as to remove part of gas and inclusions, excessive calcium line is fed into the molten steel after being broken in air, and then the molten steel is softly blown and stirred for over 20 minutes to obtain the molten steel with ultralow oxygen and ultralow sulfur.