A high-strength high-conductivity rare earth copper-magnesium alloy contact wire comprises, by weight percentage, 0.1-0.8% of magnesium, 0.1-0.4% of nickel, 0.1-0.4% of zinc, 0.1-0.4% of silver, 0.05-0.15% of a rare earth element and the balance copper and inevitable impurity elements, wherein the rear element is one or two of cerium and neodymium. When the rare earth element is added in the form that the cerium and neodymium are mixed, the weight ratio of the cerium and neodymium is 1:1-1:2. The high-strength high-conductivity rare earth copper-magnesium alloy contact wire overcomes the technical defect that the requirements on electrical conductivity and the tensile strength of a copper-magnesium alloy cannot be met at the same time in the prior art and can meet the performance requirement of the copper alloy for the railway contact wire.