Organic cobalt salts,such as cobalt acetate and cobalt naphthenate,are synthesized by neutralizing cobalt hydrox-ide with acetic acid and naphthenic acid.The cobalt hydroxide used for synthesis of organic cobalt is required to be micron-sized,non-oxidized and low chlorine content.The preparation method of micron-sized cobalt hydroxide with low chlorine con-tent was studied,and the effect of ammonia complexation,feed liquid adding order,reductant,accumulated growth time on chlorine content,microstructure and oxidation degree of the product were investigated.The experimental results showed that under the conditions as follows：hydrazine hydrate as the reducing agent,cobalt chloride solution,ammonium hydroxide and caustic soda solution added to the reaction kettle simultaneously,the reaction pH of 10.5~11.5,NH₄⁺ mass concentration of 6~9 g/L and accumulated growth time of 40 h,the rose-red cobalt hydroxide product was obtained,whose microstructure was hexagonal crystal and mass fraction of Cl was 0.017%.