The invention discloses high-toughness and high-weather-resistance steel and a manufacturing method thereof. The high-toughness and high-weather-resistance steel comprises the following components in percentage by weight: 0.035-0.075% of C, no more than 0.30% of Si, 0.40-0.80% of Mn, 0.07-0.11% of P, no more than 0.004% of S, 0.20-0.50% of Cu, 0.10-0.40% of Ni, 0.40-0.70% of Cr, 0.008-0.016% of Ti, 0.010-0.030% of Nb, no more than 0.0050% of N, 0.001%-0. 004% of Ca, and the balance of Fe and unavoidable impurities, wherein by taking a C-Mn-P component system with low C, low Mn and high P as a foundation and through the alloying of Cu, Ni and Cr, [%C] / [%P] is controlled to be not smaller than 0.49, [%Mn] / [%C] is controlled to be not smaller than 10, the weather resistance index DNH is controlled to be not smaller than 6.50%, [%C]*([%P]+2.5[%S]) is controlled to be not more than 0.0025, [%Ca] / [%S] is controlled to be equal to 1.0-3.0, ([%Cu]+0.36[%Ni]+0.27[%Cr])*[%P] is controlled to be not smaller than 0.030, [%Ca]*[%S]0.28 is controlled to be not more than 0.002, and a TMCP (ThermoMechanical Control Process) is adopted. Therefore, the high-toughness and high-weather-resistance steel has excellent low-temperature toughness, bending cold machining characteristic and high weather resistance, and is suitable to be used as a compartment body structure of a coating-free high-speed train.