Arriva Trains Wales said the line between the two stations had to be closed for a time on Monday morning.
The device was found in a garden in St Michael's Close, Ruabon, with a cordon in place and nearby homes evacuated.
North Wales Police said the World War Two bomb turned out to be a training device so did not contain explosives.
The line was close at about 11:20 BST and reopened an hour later, according to Network Rail.
A spokesperson for Arriva Trains Wales confirmed services were suspended while a bomb disposal team was called.
The company said services between the stations faced disruption until about 13:00 BST on Monday.
The device was found by a resident living in a block of flats.
The man, who did not want to be named, said: "We were clearing up at the back of the flats and a water butt was full of old, dirty water.
"We emptied it and found this thing at the bottom. We have no idea how long it had been there."
Train services between Shrewsbury and Wrexham were disrupted and homes evacuated when a wartime training device was found near a railway line.