Bradford Council needs to build a new crematorium in North Bradford and Northcliffe Park, Shipley, is on a list of three possible sites.
Locals are up in arms over plans which they say would have a massive impact on the park, which is held in trust by the council as open space for the public.
On Saturday afternoon hundreds are expected at a demonstration, with supporters marching from the gates up to the proposed crematorium site where they will hold a rally.
People are being asked to "come along and show how important Northcliffe is to you, and help us protect this special place."
Friends of Northcliffe have been shown plans for the proposed building which they think, with car parks and a garden of remembrance as well as access roads could take up to 10 per cent of the park.
They have been told the other two sites being considered by the council are private and the "more preferred options" but fear the park could end up as the "cheap option."
Chair of Friends of Northcliffe Steve Bruzzese said: "We are sympathetic to the fact that the council hasn't made a final decision.
"However we come from the position that the land is held in trust and should be used for the recreation and benefit of the public, and it shouldn't be on the table in the first place.
"Our interest is in getting it off the table."
The proposed scheme would cut the meadow area of the park in two, affecting wildlife and plantlife and the ambience, and would also damage the woods.
Mr Bruzzese, 50, said any development was the "thin end of the wedge."
He said: "We believe there's a threat simply because detailed feasibility studies haven't yet been undertaken.
"Things are going to become tougher as central Government funding diminishes in the next spending round.
"Who is to say that Northcliffe couldn't end up as the cheap option?"
It comes as a petition to save the park has been signed by nearly 3,000 people. It will be presented to the council on October 16.
One wrote: "This was my playground as a child and as an adult an amazing place to walk and enjoy. It was my grandparents and parents place to grow vegetables. I know a place is needed for a crematorium is needed but not ‘Norky’".
A spokesperson for Bradford Council said: “We are aware of the public feeling about these proposals but Northcliffe Park in Shipley is just one of a number of sites being considered and only a very small part of the site would be used if it is ultimately chosen. “This is an early stage of a feasibility study and no decision is pending.
"If the idea is progressed further a full public consultation would be carried out which would take into account the views of the surrounding community.”