The method of controlling variables was used to control the crystallization process parameters of the glycine reaction solution to obtain a product that meets the target. The dropping temperature and dropping rate of extractant were mainly studied. Crystallization cooling rate, the effect of stirring rate on the particle size distribution of crystal products, including the effect of seed size and seed addition on the particle size distribution of glycine products. Through a series of experiments, it was proved that when the dropping temperature of the extractant is 318.15 K, the dropping acceleration rate is 0.78 mL / min, the cooling rate is 0.3 K / min, the stirring rate is 300 r / min, the seed addition amount is 5 %, the glycine crystallization effect is the best, which can achieve the purpose of improving the particle size of the product and preventing the agglomeration of the product.