The invention provides high-strength duralumin alloy applied to a mobile phone shell and a preparation method of the high-strength duralumin alloy. The used high-strength duralumin alloy comprises thefollowing components in percentage by mass: 5.00 to 10.00 percent of Zn, 1.20 to 6.00 percent of Mg, 0.03 to 0.50 percent of Mn, 0.03 to 4.00 percent of Cu, 0.01 to 0.25 percent of Zr, 0.01 to 0.30 percent of Cr, 0.01 to 0.20 percent of Ti and the balance of Al and other inevitable impurities. After thermal treatment, a plate made from the high-strength duralumin alloy provided by the invention has excellent comprehensive performances, namely the tensile strength is 400 MPa to 500 MPa, the yield strength is 380 MPa to 480 Mpa, the percent elongation is 11% to 18%, the conductivity is 25% to 44% IACS, and the rigidity is 175 HV to 220 HV.