Erectile dysfunction is the tendency of the penis to become soft after erection. Erectile dysfunction can be caused by mental and psychological factors, diabetes, adverse drug reactions and penile injury. 1. Psychological factors: excessive tension, anxiety and other psychological factors will prompt the sympathetic nerves over-excited, the release of norepinephrine caused by penile vasoconstriction, penile insufficient blood congestion will easily lead to penile erection after softening. 2. Diabetes: Diabetes can cause damage to the peripheral nerves, which may cause the blood vessels in the penis to lose control, and at the same time will make the level of androgens and other sex hormones decline, causing the penis to become soft after erection. 3. Adverse drug reactions: long-term use of drugs such as diuretics, antihypertensive drugs, antidepressants and hormonal drugs can damage the endothelium of the blood vessels in the cavernous body of the penis, and erectile dysfunction can also occur. 4. Penile injury: factors causing penile injury such as trauma to the penis or penile surgery can damage the cavernous body of the penis and reduce penile congestion, which may cause the penis to become soft easily after erection. Erectile dysfunction may also be related to poor lifestyle, cardiovascular and cerebrovascular diseases, hypertension and other causes, long-term occurrence of the above symptoms affecting the quality of sexual life, you should go to the hospital in a timely manner, under the guidance of the doctor for regular treatment.