The invention belongs to the technical field of constructional steel for ships and ocean engineering and in particular relates to steel plates for a 355MPa-level easy-to-weld ocean platform and a production process of the steel plates. Two steel plates of which the thickness specifications are [6-40]mm and [40-60]mm are comprised, wherein the steel plate with the thickness specification of [6-40]mm comprises the following chemical components in percentage by mass: 0.10-0.15 percent of C, 0.20-0.50 percent of Si, 1.20-1.50 percent of Mn, not more than 0.015 percent of P, not more than 0.005 percent of S, 0.020-0.050 percent of Nb, 0.010-0.050 percent of V, 0.008-0.020 percent of Ti, 0.015-0.055 percent of Als, not more than 0.43 percent of Ceq, not more than 0.23 percent of Pcm and the balance of Fe and inevitable impurities; and the steel plate with the thickness specification of [40-60]mm comprises the following chemical components in percentage by mass: 0.10-0.15 percent of C, 0.20-0.50 percent of Si, 1.30-1.60 percent of Mn, not more than 0.015 percent of P, not more than 0.005 percent of S, 0.030-0.060 percent of Nb, 0.020-0.060 percent of V, 0.008-0.020 percent of Ti, 0.015-0.055 percent of Als, not more than 0.12 percent of Nb+V+Ti, not more than 0.43 percent of Ceq, not more than 0.23 percent of Pcm and the balance of Fe and inevitable impurities. According to the production method, the steel plates for the easy-to-weld ocean platform are produced by adopting low Ceq, low Pcm, Nb as well as V and Ti microalloy components and a normalizing heat treatment process and are lower in production cost, even in mechanical property and favorable in welding property.