Ultrahigh strength strip steel with yield strength being 800MPa and preparation method thereof

The invention discloses an ultrahigh strength strip steel with the yield strength being 800MPa and a preparation method of the ultrahigh strength strip steel. The ultrahigh strength strip steel is prepared from, by mass, 0.05-0.10% of C, 1.1-1.5% of Mn, 0.025-0.065% of Nb, 0.06-0.15% of Ti, 0.30-0.45% of Si, 0.015% or less of S, 0.02% or less of P and the balance iron and inevitable impurities. The preparation method comprises the working procedures of hot rolling, acid picking, cold rolling, annealing and leveling. According to ingredient design, low C and Mn are adopted, no hardenable elements such as Cr and Mo are added, only a small amount of micro-alloying elements such as Nb and Ti is added, the special technologies such as hot rolling, cold rolling and annealing are adopted in a matched mode, the performance is controlled by controlling strip steel grain size, educt and separation-out time, the yield strength of the strip steel is larger than or equal to 800 MPa, the percentage elongation is larger tha