Within a certain period of time, breast milk is still nutritious after freezing. Breastmilk should be put into the freezer quickly after collection, and the temperature should be kept at about -4-20℃ for three months. The nutrients in breastmilk including protein, fat, vitamins and other nutrients will not deteriorate, and the nutrients will not be decomposed and lost. If the freezing time is longer than six months, the fat and protein content in breast milk will decrease, the pH value will also decrease, and other nutrients will also be reduced to varying degrees. Therefore, it is recommended that breast milk should not be frozen or refrigerated for too long. Collecting breastmilk is also crucial to ensure the quality of breastmilk after freezing. When collecting breast milk, pay attention to the hygiene of the container and hands to avoid microbial contamination. When using again, pay attention to slow rewarming to avoid too high temperature to make protein coagulation and denaturation.