The invention provides a method for producing bloom martensitic stainless steel through continuous casting. The method comprises the following steps of: smelting molten steel with target component; performing continuous casting, namely performing electromagnetic stirring and vibration with frequency of 2-4Hz and 115-125Vc respectively of the molten steel in a crystallizer, controlling the cooling water flow of the crystallizer to 1800-2000L/min, controlling the relationship between the pull speed and the superheat temperature of molten steel, controlling the specific water flow of secondary cooling to 0.28-0.32L/kg, and controlling the water flow distribution ratio of secondary cooling to (38-42):(28-32):(28-32); and withdrawing and straightening, controlling the pressure of front two withdrawal and straightening machines to 58-62Bar, and controlling the pressure of the follow-up withdrawal and straightening machine to 48-52Bar. Compared with the prior art, the method provided by the invention has the advantages that bloom martensitic stainless steel (for example, the size is 180*180mm-220mm*220mm) is continuously produced in a large batch; and the isometric crystal rate of the obtained bloom martensitic stainless steel is not less than 20%, the center porosity of the casting blank is not greater than level 2.0, and the central line shrinkage is not greater than level 1.5.