Jermaine Jackson -- Hit By a Smooth Criminal!

TMZ has learned ... Jermaine Jackson filed a police report claiming someone stole more than $150,000 in jewelry, furs, and clothes ... just one week after he went to court claiming he couldn't afford to pay child support.

Law enforcement sources tell us Jackson and his wife, Halina Rashid, claim in the report -- filed with the L.A. County Sheriff's Department -- someone took a Louis Vuitton bag containing the treasure trove from their Calabasas home back in September.

The home -- which Jermaine rents -- is in the same gated community Katherine Jackson is temporarily living in while her Encino home undergoes extensive renovation.

We're told Jermaine claimed the bag contained some ultra-expensive watches, among other pricey items.  Our law enforcement sources say the case is under investigation ... but so far no suspects.

A week after Jackson filed the police report, he filed docs in his child support case -- claiming he couldn't afford the $3,000/month for his kids, Jaafar and Jermajesty.  He'd like the payment reduced to $215 a month.

It doesn't take a mathematician to figure this one out.