Can I marry roman catholic boy who is from mangalore and I'm a hindu girl without converting christian? His parents are forcing to me to get converted

"Can I" has different meanings.
First, your ages. Second, what country or area. Then you have to look up the laws where you are about age and different religion.
Most young people in your situation have to run away from home together, totally disowned by both sets of parents (or one set).
Do your parents approve?
What does your boyfriend say? Why isn't he standing up for you? Is he dependent on them for money, a job, school?
MANY factors to think about, aside from laws.

Some very serious issues for you to consider

Your religious focus is very different to your intended.
It is possible for a catholic to marry a non catholic but there should be agreement of how the children will be educated in religion and how religion is handled in the household
You have to consider where you will live as Hindu people can be very intolerant of those who convert to christianity and remain in a hindu community.
You have to consider how you will handle religious matters in your day to day life, you cannot just go to a catholic church and freely join in everything they do so you will not be part of your husband's activities and visaversa.
There is the question of food, your husband will be permitted to eat certain things you are not