The invention discloses a method for improving center density of continuous cast slabs of high-level building steel. In the 
continuous casting process, the drawing speed of a 
casting machine is controlled to be 0.75 m / min-0.90 m / min; solidification 
tail end heavy reduction is adopted; dynamic secondary cooling control is adopted, and meanwhile, soft reduction and heavy reduction are adopted for carrying out reduction according to the distribution 
solid phase rate; and the superheat degree of 
tundish molten steel is controlled to range from 20 DEG C to 30 DEG C. According to the method, technical measures of stabilizing the drawing speed of the 
casting machine, reducing the superheat degree of 
tundish, carrying out secondary cooling 
dynamic control, carrying out solidification 
tail end heavy reduction control and the like are mainly applied comprehensively to reduce center 
porosity of the cast slabs of the high-building steel, then the center density of the cast slabs is improved, and 
internal quality of rolled materials is improved. For the cast slabs produced through the method, after implementation is carried out, the effect is better than that of an existing soft reduction technology, the center density is higher, the overall quality is better, and the use requirement of the high-building steel can be met better.