The phenomenon of penile weakness in the process of sexual life is the possible causes: 1, androgen secretion is insufficient, with the growth of age, androgen secretion gradually decline can appear sexual function decline, will appear erection when hardness is not enough, if sex may appear in the middle of the phenomenon of weakness, which is the natural aging process with the growth of age. 2, the male use of external drugs, such as external use of In the process of activity caused by increased venous blood flow back, the phenomenon of penile weakness.