if you're past the age of puberty you should have this situation checked out by a urologist. normally during sexual arousal the prostate gland fills with fluid. this helps keep the neck of the urinary bladder tightly closed so that no urine leaks out during ejaculation. in pubescent boys before all the internal male reproductive structures have matured it's not uncommon for urine leakage to occur with ejaculation. after these structures have fully matured you shouldn't have that problem. if you do like i said you should see a urologist. this is not an emergency situation but it's certainly something you should have checked. you don't want to take chances with your reproductive health. wishing you all the best!
as a man why do i have urine instead of semen for ejaculations?