In the field of assisted reproductive technology, the quality of embryos plays a decisive role in determining the success of IVF transfer. In clinical work there are many couples with repeated IVF failures because their embryos always show a large, unpredictable and recurrent amount of cytoplasmic fragmentation. the inability of the IVF culture environment to perfectly mimic the in vivo environment resulting in embryos not adapting to the in vitro culture environment may also be one of the reasons for the large amount of fragmentation. In the latest domestic trial data, 80 embryos were cultured under the PRIMO Vision monitoring system from fertilization to day three. Mitosis is a critical period for embryos to produce fragmentation, especially in highly fragmented embryos. Irregular movements prior to mitosis accompanied by changes in embryonic cytoplasmic morphology may represent an unstable cytoskeleton. There may also be other evidence that cytoplasmic fragmentation is caused by cytoskeletal disorders. Day 3 embryos are generally not as good as day 5 embryos. The egg is freshly removed, is only single-celled, and develops and divides in culture 12-24 hours after fertilization, so by day 3 it is generally a 4-8 cell embryo. By the fifth day, the embryo develops into approximately hundreds of cells and is called a blastocyst, which has a relatively higher success rate of being transferred. The main parameters we commonly use to evaluate the quality of embryos at the oogenesis stage include the number of oocytes, the symmetry of the oocytes and the fragmentation of the cytoplasm. Embryos with 8 oocytes on day 3, uniform oocyte size and less than 10% fragmentation are considered as high quality embryos. The transfer of high quality embryos results in a high “carry home” rate. What are non-high quality embryos? On the third day after egg retrieval, embryos that are normally fertilized and developing at a normal rate are defined as high quality embryos if they are 7 to 8 cells in size and have no or less than 15% fragmentation. How does fragmentation occur? Fragmentation is a sign of apoptosis. When an embryo is stressed by its own causes or by the environment in vitro, it will generate DNA repair mechanisms and expel cellular components that are harmful to the organism, resulting in fragmentation. Therefore, the more fragmented an embryo is, the worse its growth potential is likely to be, and this becomes an important indicator of a good or bad embryo. Generally, the third day embryos of grade 1 and grade 2 are very good. Grade 3 are a little worse, but still usable. The goodness of the embryos is also related to the age of the couple. For the same level 1 and 8 cells, the chromosomal coefficient of variation is very low in young women, while the coefficient of variation is much higher in older ones. In conclusion, non-good quality embryos are not always bad embryos, and embryos with excessive fragmentation can also be cultured in blastocysts to prolong their culture time and be able to eliminate poor quality embryos. The process of prolonging embryo culture naturally eliminates poor quality or even defective embryos, so that the relatively “good” embryos will stand out and grow into blastocysts. The bodies of both men and women are fundamental in determining the quality of embryos, and the nutritional regimen, exercise and lifestyle of the couple during the first trimester are extremely important in order to have quality eggs and sperm for quality embryos.