The invention discloses high-drawing-speed sheet billet peritectic steel continuous casting crystallizer casting powder and a preparation method thereof. According to the raw material formula, the casting powder comprises, by weight, 57%-60% of aedelforsite, 7%-9% of fluorite, 8%-10% of sodium carbonate, 0%-2% of lithium carbonate, 7%-9% of glass powder, 3%-5% of bauxite, 4.5%-4.7% of carbon black and 5%-5.5% of graphite. According to the chemical composition, the casting powder comprises, by weight, 36.8%-38.3% of calcium oxide, 23.5%-25% of silicon dioxide, 2.9%-3.4% of magnesium oxide, 3.1%-3.7% of aluminum oxide, 4%-4.2% of sodium oxide, 0-1.3% of lithium oxide and 7.8%-8.5% of fixed carbon, casting powder basicity, namely CaO / SiO2, is 1.50-1.54, the melting point is 1,050 DEG C-1,100 DEG C, and the viscosity is 0.2-0.25 Pa.s at 1,300 DEG C. The casting powder can effectively solve the problems that during continuous casting, crusting and slag inclusion of casting powder of peritectic steel happen, and the surface of a casting blank cracks and is prone to breakout by sticking. Besides, the casting powder has the advantages that slag melting in a crystallizer is uniform and stable, and the surface quality of the casting blank is good and not prone to breakout by sticking.