Abstract: In order to effectively control the particle size of nano-sized zinc oxide prepared by ammonia process,leaching stock solution was diluted with a certain amount of purified water before ammonia distillation process,which could increase the quantity of crystal nucleus generated by initial precipitation and make particle size of precipitate more uniform and refined.Meanwhile,it was found that distilled ammonia residual liquid could not be served as diluent of leaching stock solution for recycling.Also,heating method of ammonia distillation will affect the particle size of nano-sized zinc oxide.Particle size of prepared nano-sized zinc oxide can satisfy the requirements of  GB/T 19589—2004,when direct steam heating was selected and mass concentration of zinc in the solution was less than 0.3 g/L. 