Staff have to pay up to £180 a year to park on hospital grounds, which brings in more than £250,000 for the hospital trust.
Justice For Nurses Walsall, which has organised the petition, hopes to get 5,000 signatures.
The campaign group called the charges a 'shameful hidden tax' on those tasked with caring for sick and vulnerable people within the community.
A statement, published on its petition page, said: "They work long hours under tremendous amounts of pressure.
"It's about time we appreciate the sacrifices that many of them make on a daily basis.
"Walsall Manor Hospital is charging its staff extortionate figures to park their vehicles, just so they can come to work.
"For many of them public transport just isn't an option.
"With cut backs across the board and pay freezes being implemented as we speak, the extra parking charges are simply unsustainable.
"Many of the parking facilities provided are also undersized and heavily inadequate.
"Staff are often left struggling to find spaces and forced to park further and further away."
The group said it was calling on the board of directors to show how much they appreciated the great job staff were doing by abolishing parking charges as a 'sign of gratitude'.
It also proposed starting a free of charge parking permit system for all qualifying staff based at the hospital.
Richard Kirby, Chief Executive at Walsall Healthcare NHS Trust, said staff were encouraged to cycle to work and were offered discounts for using public transport.
He said: "We offer our staff a number of car parking options both on and near to the Manor Hospital building and this ranges from between £15 to £25 per month dependent on where the staff member chooses to park.
"Most of the spaces allocated are at the £15 per month rate. Part time staff pay half this charge.
"The majority of NHS trusts charge staff to park on their premises and we understand that we are the lowest charging trust amongst our neighbours."
Mr Kirby said the trust had generated £264,349 from parking permits during the 2015-16 financial year.
He said: "The revenue is used to maintain upkeep of car parks, such as security measures on the site, including extra lighting.
"We also encourage staff to adopt greener methods of travel through our cycle to work scheme and discount travel passes for public transport."