Abstract: The nucleating and growing condition of crystal grain was controlled by hydrolysis-negative micro-pressure ammonia distillation. The basic zinc carbonate meeting the requirement for feed supplement was prepared from refined zinc ammonium carbonate solution. The exhalation rate of zinc was higher than 98.0 %, the content of main component zinc in products was higher than 57.5 %, the particle diameter of products was smaller than 200 nm and their loose smut of wheat thickness was 0.1-0.25 g/cm^3.