Mark Vine is wanted for questioning over more than a dozen break-ins in Hassocks and Ditchling.
In each case the homes were entered and searched after the owners went out in the middle of the day.
The thieves took thousands of pounds worth of expensive jewellery during the burglaries as well as computers, cash, cameras and collectable ornaments.
Sussex Police launched Operation Magpie to tackle burglary across the county.
A reward of £500 is now being offered for information that leads to the arrest and conviction of whoever is responsible for the burglaries.
Detective Constable Dave Wadley, of the West Sussex Priority Crime Team, said: “Vine is 36, white, 5ft 8in and of proportionate build. He has short black hair and green eyes.
“We believe he is in Brighton and Hove, Portsmouth or Mid Sussex and that he is using the rail network to get around.
“I am keen to speak to anyone who recognises him or who may know where he is. Please keep an eye out if you use the trains to see if Vine is using them at the same time.”
Anyone with any information should call 101 quoting Operation Bullet, email [email protected] or call the independent charity Crimestoppers anonymously on 0800 555111.