Grease soundtrack star and Four Seasons lead man Frankie Valli is in the midst of a bitter divorce from his wife of 27 years.

Randy Valli — who was married to Frankie for 27 years — has filed legal docs, asking the divorce judge for attorney’s fees, but what’s really interesting is how much money he makes — and she already gets.

Apparently, the business has been very good to Frankie.

According to legal docs, Frankie is raking in more than $515,000 per month — presumably a big chunk is from “Jersey Boys.”

That said, Randy is looking to her share on top of what she already gets.

But 51-year-old Randy is already getting a big piece of the 77-year-old Frankie. For starters, she gets $30,000 a month — $5 grand in spousal support, and $25,000 grand a month in royalties from “Jersey Boys.”

And this is interesting … even though she’s pulling in more than a third of a million bucks a year, the docs say she’s getting $810 a month in public assistance. It looks like that money is for a portion of his SSI because she’s taking care of their minor children.