The invention relates to a method for preparing cobalt hydroxide, in particular to a method for preparing battery-grade superfine flaky cobalt hydroxide, and aims to provide a method for preparing battery-grade superfine flaky cobalt hydroxide which is stable in particle, not easy to aggregate or oxidize, large in contact area with lithium cobalt oxides and capable of effectively improving the conductivity of a cathode material. Flaky cobalt hydroxide with a small particle size is synthesized from cobalt salt as a raw material and sodium hydroxide as a precipitator by using a liquid phase precipitation method, flaky disposable particles which are complete in crystal form and smaller than 1mu m in particle size can be prepared in the synthesis process, and the morphology and the particle size of original disposable particles can be maintained through airflow crash.