The red color of sperm during ejaculation indicates the presence of hematospermia, which may be caused by factors such as damage to the reproductive system, infection of the reproductive system, and tumors of the reproductive system. 1. Reproductive system injury: for example, if you exert too much force during sex or suffer acute injury to the lower body, resulting in localized damage to the reproductive system, when ejaculating, the blood mixes with the semen, which can lead to hematospermia. 2. Reproductive system infection: due to the existence of infection in the reproductive system, it may lead to local bleeding, which can cause hematospermia, and the common diseases are prostatitis or seminal vesiculitis, which may be accompanied by ejaculation pain, perineal swelling and pain and other symptoms. 3. Tumor of reproductive system: after necrosis of tumor surface tissues, it may cause bleeding, and ejaculation with blood may occur. Common diseases are prostate cancer, which may be accompanied by urinary difficulty, frequent urination, urgency and other symptoms. The red color of sperm during ejaculation may also be due to other reasons. It is recommended to consult a doctor in time for appropriate examination and treatment to avoid the continuous aggravation of the lesion.