Sperm motility trajectory analysis refers to the use of continuous exposure photographic technique to determine the speed of sperm movement through the distance of sperm movement within a certain period of time, so as to determine the sperm motility, especially the forward motility of sperm, which is one of the important factors in determining whether sperm can be fertilized. In addition to the factors that determine whether sperm can be fertilized, there are other factors including semen color, quantity, liquefaction time, sperm density, percentage of abnormalities, etc. In the fourth edition of semen examination standards, sperm motility is divided into four grades, A, B, C and D. Grade A refers to fast forward motion, grade B refers to slow forward motion, grade C refers to non-forward motion, and grade D refers to rapid slow or immobile sperm. In the fifth edition of the standards, the percentage of forward motion was changed to a normal value of ≥32%.