A team of volunteers, led by Clwyd-Powys Archaeological Trust, are excavating the remains of a large building close to the castle.
Although the use of the building has not been confirmed, some of the artefacts recovered from the initial dig suggest part of it may have been used as a smithy.
Visitor experience manger Jon Hignett said discoveries already made included Victorian and Georgian pottery, historic lead working, stained glass and clay pipes.
People visiting the castle over the last two weekends were able to see some of the discoveries and the volunteers at work.
"Even after 700 years Chirk Castle and its landscape hold many mysteries," Mr Hignett said.
"Over the last few years, we’ve been carrying out research to understand more about the castle and its surroundings in more detail after an archaeological survey hinted that there is still lots waiting to be discovered.
"Last year, an excavation revealed the outer walls of a large two-storey building on the west side of the castle. The purpose of the building is unknown, but some of the artefacts recovered from the initial dig suggest part of it may have been used as a smithy."
The Clwyd-Powys Archaeological Trust said that the project has been funded by Cadw and the National Trust Wales with additional support from the Clwydian Range & Dee Valley AONB - and made possible by the fantastic volunteers that were involved.
It said among the finds were pieces of delicate stained glass.
Chirk Castle's grounds are currently open to Welsh visitors only but Mr Hignett said he hoped that would change for December.
The castle is planning a Christmas tree festival based on a pantomime theme.