Mr. Zhang failed to get his wife pregnant after 2 years of marriage. Six months ago, he had a routine semen examination at the hospital, and the report showed that the sperm density, motility and viability were normal. After half a year of effort, he still did not see any response from his wife. Was it the wife’s problem or was Mr. Zhang’s own semen situation not stable enough? After examining his wife, everything was normal, and his own semen routine was normal as usual, but this result made Mr. Zhang puzzled. At present, routine semen analysis can mainly provide information about semen volume, liquefaction, sperm density, sperm vitality, viability and sperm morphology. In fact, the analysis of these contents is still very superficial compared to the evaluation of male fertility. The focus on sperm density and viability is indeed a key indicator for conceiving the female partner. During sexual intercourse, semen is ejaculated into the vagina and sperm swim out of the seminal plasma, crossing the cervix, the uterine cavity, the isthmus of the fallopian tube and finally reaching the abdomen of the fallopian tube to meet the egg. The female reproductive tract is filled with viscous fluid and the mucous membrane of the isthmus of the fallopian tubes forms zigzag folds, which pose a great resistance to sperm transport and also act as a screening screen for sperm, so that only sperm with strong motility and proper movement can reach the egg. Only sperm with high motility and proper motility can reach the egg. Therefore, even a large number of inactive sperm is useless. However, once the sperm has reached the intended site, is it always possible to conceive a woman? The answer is no, and it is time to learn more about the function of sperm and their fertilization potential. As we know, human sperm are tadpole-shaped, about 60 μm in length, with a head and a tail. The head consists of a highly condensed nucleus and an acrosome in front of the nucleus, which contains genetic material, while the acrosome contains a variety of enzymes associated with sperm crossing the radioactive crown, zona pellucida and oocyte membrane. The role of acrosomal proteases and hyaluronidase is most important during sperm-egg fertilization. When the spermatozoa are first united with the egg, they are blocked by the oocytes surrounding the egg and must cross the base of the oocyte and then “march” towards the zona pellucida, a process known as the acrosome reaction. When the acrosome reaction begins, the acrosome first swells, the cell membrane of the sperm adheres to the outer membrane of the acrosome, fuses at multiple points, and ruptures at the point of fusion. The acrosome reaction is the key change in spermatozoa during fertilization, and only spermatozoa that have completed the acrosome reaction can fuse with the oocyte and achieve fertilization. A “malfunction” in this process may make it difficult for a man to have a normal child. As a result, the acrosome reaction of spermatozoa is often checked for normalcy in clinical practice, including acrosomal enzymes and hamster egg penetration tests, the latter of which is less commonly performed in China due to the need to breed hamsters, which is a tedious procedure. In conclusion, only through a complete fertility evaluation can fertility be clarified and then targeted prevention and proper treatment can be carried out, and the previous one-sided understanding of focusing only on sperm density and viability needs to be further corrected.