The invention discloses a calcium phosphate coating capable of controlling and separating out rear-earth ions and a preparation method thereof. The calcium phosphate coating is prepared from titanium powder, composite ceramic powder and Dy2O3, wherein the dosages of titanium powder and composite ceramic powder are (0%-70%):(30%-100%) by weight percent; the dosage of Dy2O3 is 0.2%-0.8% of that of the composite ceramic powder. The preparation method comprises the following steps: mixing the titanium powder, the composite ceramic powder and the Dy2O3 powder uniformly, ball-milling and mixing to obtain a laser cladding calcium phosphate coating powder material; then pre-placing the prepared powder material on the surface of titanium alloy TC4, and preparing the calcium phosphate coating with a laser cladding process. The calcium phosphate coating and the preparation method provided by the invention can form a bioactive coating on the surface of titanium alloy; an artificial joint coated with the coating has characteristics of controlling and separating out the rear-earth ions, inhibiting osteoclast activity, and preventing wear debris of the artificial joint after being implanted in the human body.