A penis that is not painful when it is weak but painful when it is erected may be related to penile structural abnormalities, trauma, and circumcision. 1. Abnormal penile structure: For example, if the penis is curved, sclerosis, etc., a certain area of the white membrane of the penis is thickened, and there is a pulling sensation, which will lead to pain when the penis is erected. 2. Trauma: there may be other small wounds on the penis, when the penis is engorged with blood, it will pull on the wounds and cause pain. 3. Circumcision: If the patient himself has a long foreskin or adhesion, when the penis is erected, the foreskin is turned down, which will also cause the feeling of penile pain. Penile weakness does not hurt, erection pain can also be seen in other reasons, it is recommended that timely medical treatment, follow the doctor’s instructions for relevant examinations, in the doctor’s help to deal with or treatment.