The invention relates to a production method of tempering type low-yield-ratio bridge steel. The process route comprises molten iron pretreatment, converter treatment, refining, continuous casting, heating, rolling, cooling and tempering, and the steel is prepared from the following chemical components: 0.07%-0.09% of C, 0.20%-0.30% of Si, 1.52%-1.60% of Mn, less than or equal to 0.015% of P, less than or equal to 0.003% of S, 0.020%-0.045% of Alt, 0.01%-0.030% of Nb, 0.012%-0.020% of Ti, 0.16%-0.20% of Cr, 0.08%-0.12% of Mo, 0.16%-0.20% of Cu, less than or equal to 0.22% of Pcm and the balance of Fe and inevitable impurities. The steel produced through the method has the advantages of being low in cost, narrow in component and the like, the produced steel plate with the thickness of 6-50 mm is larger than or equal to 420 MPa in yield strength, smaller than or equal to 0.80 in yield ratio and larger than or equal to 200 J in impact toughness at the temperature of -40 DEG C, and the steel plate is low in manufacturing cost, low in yield ratio, high in strength and high in low-temperature toughness.