I'm a college student who is writing a paper about sacrifice for
love. because i believe the only why to show a person how much you
love he/her is   depend on how much you can sacrifice for he/her.  for
example, parents can sacrifice their lives to save their childern from
danger...so on.  I would like to know why and what's the psychological
thinking of the person who sacrifice for love .   also give me as many
refernces relates to that topic as possible.

Quite a lot of references to this idea in the New Testament ...

John 15:13
Romans 5:6-8
Galatians 2:20
etc

>> i believe the only why to show a person how much you love 
>> he/her is depend on how much you can sacrifice for he/her.

I disagree with your premise. There are many, many ways to express
your love which do not involve sacrifice. They involve giving, but not
at any expense or hardship to the giver.

After twenty-five years of marriage, I know that my husband loves me
when he changes the oil in my car without my having asked him to do
so. I know that he loves me when he fixes dinner and washes the dishes
because he sees that I am not feeling well. I know he loves me when he
fetches himself a drink and automatically wonders "Would Pink like
one, too?"

Love, over the long term, is not typically defined by great
sacrifices. The small tasks done for love, day after day and year
after year, have meaning. Without them, a single large sacrifice is
just a melodramatic gesture.

I think another way to define sacrifice for love is to not have any
expectations of getting love or anything else in return for whatever
it is you are giving as an expression of love. Pinkfreud has the right
idea and I have to say it took me a while to rid my mind of the
romantic notions of love and understand that love can come in many
forms and through the most mundane tasks. I too have a husband who
washes my car and fills it with gas and performs countless loving
gestures that in my former romanticized state of mind could not have
possibly recognized as love. Thank God for maturity!
good luck with your paper...