The invention specifically relates to a zirconium-based alloy for a water-cooled nuclear reactor, belonging to the technical field of special alloy materials. The zirconium-based alloy comprises, by weight, 0.20 to 0.60% of Sn, 0.20 to 0.40% of Nb, 0.30 to 0.50% of Fe, 0.15 to 0.30% of Cr, 0.002 to 0.15% of V or Mo, 0.002 to 0.02% of Si or S, 0.06 to 0.15% of O, less than 0.008% of C, less than 0.006% of N, with the balance being zirconium. According to the invention, on the basis of a Zr-Sn-Nb alloy, other components used for improving alloy performance are added, and proper component contents are selected; the performance of the zirconium-based alloy provided by the invention meets requirements of high burn-up of the water-cooled nuclear reactor on a core structural material. Pipes and boards prepared from such prototype alloy have improved homogeneous corrosion resistance in pure water out of a reactor, especially in an aqueous lithium hydroxide solution. According to test results in detailed description of the invention, it is considered that the zirconium-based alloy has more excellent homogeneous corrosion resistance, high creep resistance and fatigue resistance and anti-irradiation growth performance when used in a reactor.