Abstract: The present invention relates to a process for preparing a carrier used in olefin polymerization catalysts, comprising suspending anhydrous magnesium chloride in an inert hydrocarbon solvent and then under stirring, activating the magnesium chloride with a C2-C8 alcohol at a temperature of 30° C. to 200° C., with the molar ratio of said alcohol to said magnesium chloride being in the range of 0.05 to 2.5. Moreover, in order to make the resultant catalysts more active, the process according to the present invention can further include a pre-dispersing step conducted prior to the activation step, wherein the dispersing agent is alkoxides of titanium or C3-C8 alcohols and the molar ratio of said dispersing agent to said magnesium chloride is 0.01 to 2.0. The catalyst prepared from the resultant carrier is suitable for polymerizing ethylene or compolymerizing ethylene with alpha-olefin.