The invention discloses a bloom continuous casting soft-reduction process used in steel production, and in particular relates to a method for controlling a bloom continuous casting dynamic soft-reduction pressure interval. The pressure interval is determined according to the central solid-phase rate of each casting blank section in the direction of blank drawing; the central solid-phase rate of each casting blank section relative to the upper limit of the pressure interval is less than or equal to the fs, namely Maxopt which is the maximum value of iopt, of each solute element, wherein the fs and iopt are the central solid-phase rates of a casting blank section relative to the minimum Ki of the solute elements; the Ki is the average solute aliquation index of the solute element i in two phase regions when each casting blank section is slightly pressed; furthermore, the central solid-phase rate of each casting blank section relative to the lower limit of the pressure interval is more than or equal to the fs, namely Minopt which is the minimum value of iopt, of each solute element. The pressure interval determined by the method can effectively improve central aliquation and also reduce cavity, looseness and crack; and the pressure interval has stable use effect and is suitable for bloom continuous casting production.