Perineal pain at the moment of ejaculation may be due to diseases such as seminal vesiculitis, prostatitis, and urethral calculi. 1. Vesiculitis: mostly caused by pathogenic bacteria such as E. coli. Symptoms include sudden onset, perineal pain, and pain in the groin; frequent urination, painful urination, pain after ejaculation, and sometimes bloody semen. 2. Acute prostatitis: it can also lead to such symptoms. Acute prostatitis usually occurs suddenly, often with frequent urination, painful urination, hesitant urination and other symptoms. 3. Urethral calculi: similar symptoms can occur, symptoms include difficulty in urination, pain in urination, while the pain can radiate to the head of the penis and other parts. Symptoms such as pain after ejaculation and difficulty in urination may also occur. The above symptoms may also be caused by other factors, it is recommended that patients go to the regular hospital in time for treatment, and strive for early recovery.