Carnitines are important conditionally essential nutrients in the organism, with extensive physiological functions, and highly concentrated in the epididymis and sperm. Carnitines play an important role not only in initiating sperm motility, promoting sperm maturation and enhancing sperm fertilizing, but also in regulating Sertoli cell function, protecting sperm against oxidative damage, reducing apoptosis of spermatogenic cell and inhibiting sperm aggregation. Accordingly, the objective of this review is to summarize the multifunctional roles of carnitine in male reproduction.