Provided in the present invention is the use of a nerve growth factor in preparing a drug for treating hypogonadism syndrome in middle-aged and elderly males, which is mainly used to prepare a drug for treating decreasing human testosterone levels due to the reduction of leuteinizing hormones secreted by the pituitary gland or Leydig cell ageing, wherein the nerve growth factor is derived from human beings, mice or rats, preferably from human beings. The amino acid sequence of the nerve growth factor is shown as SEQ ID No:1-3.