The invention discloses peritectic steel continuous casting covering slag, which comprises the following components in percentage by weight: 70 to 78 percent of calcium silicate, 4.5 to 8.5 percent of kieselguhr, 4.5 to 9.5 percent of insulating brick powder, 1 to 7 percent of cryolite, 1 to 7 percent of high-temperature aluminum oxide, 0.5 to 4.5 percent of carbon black, 1 to 5 percent of petroleum coke and 0.5 to 5 percent of expanded graphite. The invention has the advantages that: the peritectic steel continuous casting covering slag has high physical performance and operational performance, and can meet the requirement of peritectic steel continuous casting production of steelmaking enterprises in China at present and create huge economic and social benefits; and the invention has the characteristics that: 1, the covering slag overcomes the surface defects of casting blanks effectively, and the defective index can be reduced by over 20 percent; 2, the covering slag special for special steel can be used for producing the special steel which are not produced previously; and 3, the covering slag is stable, ensures that the production is smooth, and prevents loss caused by accidents such as bleed-out and the like.