A foldable stroller frame includes a connection unit interconnecting two opposite foldable side frame units, each of which includes a front leg and a handle rod connected pivotally to each other, and a rear leg connected pivotally to the handle rod. The connection unit includes four bottom rods each having a first end connected pivotally to a connecting seat, and a second end connected pivotally to a respective one of the front and rear legs of the side frame units. When the connecting seat is pulled upwardly from a lower used position, the second ends of the bottom rods move radially toward each other, whereby the side frame units are folded and move toward each other.