The main difference between second generation and third generation IVF is the different application of people, the second generation IVF is mainly for patients with severe oligozoospermia, weak spermatozoa, teratospermia or azoospermia in the male partner, and the third generation IVF is mainly applied to patients with single gene disease in the couple. Second-generation IVF mainly helps the following types of patients to get pregnant, such as severe oligospermia, weak spermatozoa and teratogenesis, etc. For patients who need to undergo preimplantation embryo genetics testing, the specific operation is to select semen. After semen optimization, sperms with normal appearance and good vitality are selected and added directly to the eggs to complete the entire fertilization process. Third generation IVF should first perform embryo chromosome examination on all the well-scored embryos before embryo transfer, and screen out the embryos with normal chromosome examination. Third-generation IVF is a method of assisted conception used primarily to prevent the transmission of hereditary diseases to the next generation, in order to prevent one or both of the patient’s spouses from developing a hereditary disease that runs in the family. Second and third generation IVF have their own advantages and the best treatment plan needs to be taken under the advice of a doctor.