A method for growing a single-crystal silicon ingot and a single-crystal silicon ingot includes, during an initial stage of body growing process of the single-crystal silicon ingot, controlling an initial height of a horizontal magnetic field to be higher than a free surface of silicon melt. The method further includes, during the body growing process of the single-crystal silicon ingot, adjusting the horizontal magnetic field on convection intensity of the silicon melt to make oxygen concentration of the single-crystal silicon ingot to be decreased in an axial direction from a head portion to a tail portion.