A foldable stroller frame includes: two opposite foldable side frame units; and a foldable middle support interconnecting the side frame units. Each of the side frame units includes a handle rod, a first leg pivoted to the handle rod and adapted to be connected to a first stroller wheel, a second leg pivoted to the first leg and adapted to be connected to a second stroller wheel, and a connecting slider mounted slidably on the second leg. The handle rod has a lower end portion pivoted to the connecting slider so as to be co-slidable with the connecting slider on the second leg.