The invention relates to the technical field of fire-resistant weather-proof steel plates for building structures, in particular to a fire-resistant weather-proof steel plate for 690MPa-grade buildingstructure and a manufacturing method thereof. The steel plate consists of the following chemical components in percentage by weight: 0.05%-0.10% of C, 0.10%-0.40% of Si, 1.20%-1.80% of Mn, less thanor equal to 0.010% of P, less than or equal to 0.003% of S, 0.7%-1.1% of Ni, 0.65%-1.10% of Cu, 0.20%-0.60% of Mo, 0.07%-0.12% of Nb, 0.05%-0.075% of V, 0.02%-0.035% of Ti, less than or equal to 0.0025% of B, 0.01%-0.04% of Al, and the balance of iron and inevitable impurities. The fire-resistant weather-proof steel plate adopts a two-phase region once thermal treatment process to obtain a reversetransformed austenite structure which is proper in proportion and stable, so that a multi-phase structure which consists of tempered-state martensite, a nano precipitated phase and retained austeniteis finally obtained. A smelting and continuous-casting process scheme realizes low-phosphor low-carbon control. The product has high strength and toughness, high plasticity, a low yield ratio, and excellent fire resistance, weather resistance and lamellar tearing resistance.