The invention discloses a high-strength plate spring. The high-strength plate spring is prepared from the following components in percentage by weight: 0.55%-0.60% of C, 0.20%-0.37% of Si, 0.85%-0.95%of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.85%-0.95% of Cr, 0.20%-0.40% of Ni, 0.03-0.05% of Nb, less than or equal to 0.005% of Al, less than or equal to 0.15% ofCu, less than or equal to 0.005% of Pb, less than or equal to 0.015% of As, less than or equal to 0.015% of Sn, less than or equal to 0.005% of Sb, less than or equal to 0.005% of Bi, and the balanceof Fe and unavoidable impurity elements. The produced and machined plate spring is high in strength, high in fatigue failure resistance capability and relaxation resistance capability, pure in steel,low in gas content, uniform and stable in component, good in comprehensive mechanical property, long in service life and low in cost.