The city council is about to prepare a feasibility study into the scheme at Charing Cross, which would follow work to widen pavements in nearby Sauchiehall Street.
The new park is expected to cover the deep M8 cutting south from Tay House, which is built across the motorway on an unfinished bridge south of Sauchiehall Street.
It could extend as far as Bath Street, but the city council said it might not go further south, to the Mitchell Library, which borders the motorway.
Council leader Frank McAveety said: "This is a truly inspiring project, but also one that is complex as it is ambitious.
"We must get the groundwork right and take time to create something that benefits the city while delivering a new public space that attracts and connects people and places.
"Coupled with the other projects coming forward as part of the Sauchiehall and Garnethill regeneration project, it will ensure we make this a prominent place in the city’s life.”
An artist's impression of how the park could look has been produced by architects Keppie Design, but the council is to hold a design competition to choose the winning scheme.
A council spokesman said: "We will look to start procurement for the feasibility work in late spring, and the actual investigations/modelling is expected to begin in the autumn."
The study is expected to take a year, with a final decision due to be taken around the summer of next year.
It will include considering how to give pedestrians priority in crossing nearby roads so they can reach the park, and its impact on traffic flows.
Research on how other cities have built similar parks will be done, including Klyde Warren Park, which was built over the Rogers Woodall Freeway in Dallas in 2012.
Meanwhile, work is due to start this summer to create an "avenue" on Sauchiehall Street by narrowing the road, installing a cycle lane and planting trees.
Other plans include making Renfrew Street - where Glasgow School of Art is sited - as an "Avenue for the Arts".