West Oxfordshire Green Party (WOGP) appealed to revive the decommissioned tracks in the hope that 120 business leaders meeting at Witney Lakes Resort next week will back the plan.
The special meeting of rail bosses, councillors, and various chambers of commerce will be debating the future of the Cotswold train line.
Yarnton Station is a link station to the in-use Oxford to Hanborough route.
It closed in 1962, which marked the end of passenger trains between Witney and Oxford.
WOGP spokesman Maurizio Fantato said: “Opening and redeveloping an interchange point at Yarnton station would in our opinion offer a good opportunity to provide a long term solution to the traffic problems.
“We stress, just as we mentioned before, that this interchange node should be seen as the first step towards a much more ambitious and useful rail link towards the west of the district, as far as Carterton.”
The half-day conference, organised by West Oxfordshire District Council (WODC) and train operator GWR, is to focus on increasing local services and improving long distance services to London and Heathrow Airport.
The Greens and Witney Oxford Transport group have previously called on Oxfordshire County Council (OCC) to back the project to reopen the station instead of pouring £35million into the A40 to ease congestion.
OCC has allocated £35m to improve the road and build a park and ride at Eynsham, with work set to start in 2017.
Network Rail spokesman Victoria Bradley said it does not have funding to reopen the station at Yarnton, but said a business case could be developed by a local authority such as WODC.
WODC said it sees rail as vital to the development of tourism and to encouraging visitors from London to see Oxford, Worcester and Hereford using the Cotswold Line.
Leader of the council, Sir Barry Norton, said: “The further development of the Cotswold Line is essential for continued economic growth in the area.
“We really want to hear from businesses about how it would benefit them directly and this will have a major influence on development going forward.”
The conference next Friday, chaired by Lord Richard Faulkner, is fully subscribed.
The Cotswold Line includes stations at Oxford, Hanborough, Charlbury and runs through to Hereford in Herefordshire.
Regional development manager at GWR Tom Pierpoint said: “The event is an opportunity to present a vision for the future of rail from Hereford to Oxford towards London.
“It will discuss improvements already committed through to December 2018, including brand new trains and a new station at Worcestershire Parkway and set out the potential for more improvements including faster and more frequent services beyond 2018.”
But the closed meeting has been criticized by the local Green party for not being accessible to the public.
Mr Fantato added: “We are not sure why the organisers decided to limit the event to the business community of West Oxfordshire. We strongly feel that any form of public transport should involve the public too.
“We welcome, however, any opportunity that may provide an arena to discuss the poor rail services (in comparison to similar other areas of southern England) that are available in our district.”