The Serie A club share the stadium with rivals Inter but have begun working with the company behind Bayern Munich's Allianz Arena and the Bird's Nest Olympic Stadium in Beijing on a new venue.
San Siro, which formerly had a capacity of 100,000, currently holds just over 85,000 fans - although Milan attendances have gradually dwindled in recent years.
In a statement confirming the plans, Milan also revealed the stadium would have an 'English model', in that it will be easily reached by public transport.
The stadium will be less than 30 metres high from ground level and be built using soundproofing technologies, to limit noise in what is an urban area.
Announcing their plans, Milan called the potential new structure "A unique place, planned in collaboration with the Milan Polytechnic Architecture Department and that aims to be open seven days a week and not just on match days.
"It plans to hold 48.000 spectators and aims to provide a truly exciting experience with particular attention towards families, with the latest comforts and the best in security."
