The success rate of IVF is affected by the quality of embryos, endometrial tolerance and other factors. In IVF we select high quality embryos to be placed in the uterine cavity, but the current national and international embryo implantation rate is only about 20-40%, with blastocysts being a little higher, but none of them are likely to reach 100%. This is because the current method of assessing the quality of embryos is based on morphology, that is, based on the way the embryo looks to predict whether it is of good or bad quality, just like “judging a book by its cover”, at present there is no way to really know which embryo can be successfully implanted, but only probabilistically speaking, the possibility of the successful implantation of a well-modeled embryo is high. The probability of successful implantation of embryos with good morphology is high. In addition, whether the embryo can be implanted or not is also affected by the tolerance of the endometrium, which is like the land. If the land is not good, the seed, even if it is good, will not be able to germinate and grow.