The invention relates to a method for manufacturing section steel with high strength and high toughness by using a hot-rolling steel plate. In the method, the hot-rolling steel plate is adopted, cut by a fixed size, heated to 1050DEG C to 1100DEG C by an induction heater under the clamping of a horizontal roller and an upright roller and then bent and manufactured into section steel by using a roller type forming machine set, the section steel is sent into the induction heater, water-cooling quenching is carried out on the section steel after being heated to 930DEG C to 960DEG C within the time of 60 to 150 seconds, the quenching and cooling speed of the section steel is greater than or equal to 8DEG C/S, the section steel after quenching is heated to 630DEG C to 660DEG C by a tempering induction heater to carry out tempering, the tempering time is 80 to 200 seconds, and straightening, flaw detection, surface inspection and sampling inspection are carried out after refining so as to manufacture the section steel with high strength and high toughness. The invention has the characteristics of small internal stress, high strength, high impact toughness, high shape and size precision, good straightness degree and the like. The section steel can be applied to the production of important structural parts, such as the manufacture of components comprising semilunar plates used for the connection of ocean platform racks, crossbeams of heavy-duty transport trucks and the like.