EXCLUSIVE

Jamie McCourt has filed a new lawsuit against her ex-hubby former L.A. Dodgers owner Frank McCourt ... claiming he grossly shortchanged her in the property settlement by fraudulently undervaluing their assets -- in particular the Dodgers.

In the lawsuit ... obtained by TMZ ... Jamie says based on the valuation of assets Frank's team provided ... she agreed to accept a $131 million settlement plus a few other things.

Jamie now says Frank cooked the books by undervaluing the Dodgers assets at less than 1/10 their actual value.   Jamie says their total assets were more than $1.7 BILLION. 

Jamie says based on the real numbers, she should have received more than $900 million.

Rich people's problems.