Is it normal if a girl don't have menstration at the age of 15?

Can be: As long as she has other signs of puberty, e.g., breast development, pubic hair.

Maybe,maybe not: Only 5% of normal girls in the us will not achieve menses by 14.1, and not reaching it by 15 or 3 years after breast buds appear is considered unusual.(primary amenorrhea) . I would contact her doc and schedule a visit.Referral to a pediatric endocrinologist may be the next step.