Foreskin mouth narrowing causes: 1, physiological narrowing: that is, we often say that the foreskin, children are born for the foreskin state, but with the growth and development, the speed of penile growth is faster than the speed of foreskin growth, when the foreskin natural back, narrowing can be with the development process into a normal state, but some children with the growth and development process, foreskin penis speed synchronous growth or foreskin growth speed, faster than the growth of the penis Speed, the prepuce can persist, resulting in adult narrowing of the outer foreskin; 2, traumatic stenosis: local trauma to the penis or foreskin, the formation of scarring in the healing process, scarring leads to the loss of foreskin elasticity, forming a narrow mouth; 3, chronic infection caused by the narrowing of the foreskin mouth, infection occurs, repeatedly, there can be local thickening, loss of elasticity, forming a narrow foreskin mouth.