The invention relates to an easily welded, hardened and tempered high-intensity steel plate and its producing method, which comprises the following part: C<=0.15%, 0.15%-0.50% Si, 0.80%-1.80% Mn, P<=0.02%, S<=0.01%, Mn<=0.6%, Nb<=0.07%, B<=0.003%, Ni<=1.20%, Cr<=0.80%, Ti<=0.03%, V<=0.08%, the rest Fe and unavoidable impurity. The invention smelts with the electric furnace, which is provided with the low quantity P, S and the pure steel, gets the users' favor, has the low cost and the market competitive ability, solves the problem of big crystal grain and low dynamic ductility, and is fit for producing the high-intensity steel with low draught pressure rolling mill in the other steel factory. The invention also reduces the labor strength, which saves the time of the work, improves the availability ratio of the material, and reduces the leveling expense of making the steel plate.