The penis can usually be erected but when it comes to the critical moment will be soft may be overly nervous, long-term masturbation as well as chronic prostatitis and so on causes lead to. 1. Excessive tension: If you have a lot of work pressure in your life and are overly nervous, you may have a soft moment in your sex life. 2. long-term masturbation: long-term frequent masturbation may cause the urogenital system long-term congestion, so that the central nervous system is in a state of excitement for a long time, if you do not get the appropriate rest may cause sexual nerve fatigue, cause the penis usually can be erected, but to the critical moment on the soft phenomenon. 3. Chronic prostatitis: Chronic prostatitis may cause the prostate to become congested and swollen for a long period of time, resulting in a particularly sensitive urethra, which affects the nerves of the penis and the spongy body’s response, affecting the normal sex life. There is also a psychological impact on the patient, resulting in the phenomenon that the penis can usually be erect but soft when it comes to the critical moment. Patients who have the phenomenon that the penis can usually be erected but is soft when it comes to the critical moment should go to the urology department of the regular hospital in a timely manner to improve the relevant examination and receive the correct treatment under the advice of the doctor.