The present invention relates to a method for preparing fine powdered cellulose ethers. In particular, the present invention relates to a method for preparing cellulose ethers in a cost-effective manner having high running efficiency of process, which comprises specifically regulating a reaction condition of each step to induce a particle refinement and significantly reduce a running load on a grinding process, in the reaction of treating finely pulverized celluloses with a caustic soda and reacting with an etherifying agent.