Abstract: The macrosegregation of C,P,S,Cu,Si and Mn in cast ingots of weather-resisting steel was studied by applying the technology of original position statistic distribution analysis(OPA),and the effect of rare earth elements(RE) on the macrosegregation in the steel was analyzed.The results showed that under the condition of the equiaxial crystal rate of 30% to 40% and the overheating temperature of 20 ℃ in the ingot,there was serious macrosegregation of C,S,P and Cu in the steel.C and S present center positive segregation,P and Cu the center negative segregation,and P and Cu the inverse segregation,while the solute distributions of Si and Mn were more uniform.The segregated zone of each element was of exactly the same.The solid solubility of RE in the steel were 10^-5 to 10^-4,and the soluted RE could refine dendrites and increase the equiaxial crystal rate.The macrosegregation of C,P,S and Cu was improved obviously by adding RE of 0.38% to 0.55% into the steel.