Preparation method of ultra-low carbon steel continuous casting billet, ultra-low carbon steel continuous casting billet and steel product

The invention discloses a preparation method of an ultra-low carbon steel continuous casting billet, the ultra-low carbon steel continuous casting billet and a steel product. The method comprises the steps that tundish molten steel passes through a crystallizer at the speed of 1.4 m/min to 1.6 m/min, crystallizer molten steel is obtained, and the carbon content of the tundish molten steel is smaller than or equal to 0.006%; the crystallizer molten steel is cooled, a continuous casting billet is manufactured, and crystallizer cooling comprises first cooling water in the first direction and second cooling water in the second direction; the flow velocity of the first cooling water is 5600 L/min to 5900 L/min, and the flow velocity of the second cooling water is 570 L/min to 580 L/min; when the width of the ultra-low carbon steel continuous casting billet is 900-1200 mm, the taper coefficient of the crystallizer is 1.2%; when the width of the ultra-low carbon steel continuous casting billet is 1201-1500mm, the ta