A foldable stroller frame comprising: two opposite foldable side frame units spaced apart from each other in a widthwise direction of said stroller frame, each of said side frame units including a front leg, a handle rod having a pivot end that is connected pivotally to said front leg, and a handle end that is opposite to said pivot end, and a rear leg having an upper end that is connected pivotally to said handle rod; and a foldable connection unit (2, 2') interconnecting said side frame units and including a connecting seat (21, 21'), and two hollow front bottom rods and two hollow rear bottom rods arranged radially around said connecting seat (21, 21'), each of said front and rear bottom rods (22, 23) having a first end (221, 231) that extends into and is connected pivotally to said connecting seat (21, 21'), and a second end (222, 232) that is opposite to said first end (221, 231), said second end of each of said front bottom rods being connected pivotally to said front leg of a respective one of said side frame units, said second end of each of said rear bottom rods being connected pivotally to said rear leg of a respective one of said side frame units; to unfold said stroller frame, said connecting seat (21, 21') being pushed downwardly to a used position so as to drive said second ends (222, 232) of said front and rear bottom rods (22, 23) to move radially away from each other such that said side frame units are driven by said front and rear bottom rods (22, 23) to move away from each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot away from each other and such that said rear leg and said handle rod of each of said side frame units pivot away from each other; and to fold said stroller frame, said connecting seat (21, 21') being pulled upwardly from the used position so as to drive said second ends (222, 232) of said front and rear bottom rods (22, 23) to move radially toward each other such that said side frame units are driven by said front and rear bottom rods (22, 23) to move toward each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot toward each other and such that said rear leg and said handle rod of each of said side frame units pivot toward each other. two opposite foldable side frame units spaced apart from each other in a widthwise direction of said stroller frame, each of said side frame units including a front leg, a handle rod having a pivot end that is connected pivotally to said front leg, and a handle end that is opposite to said pivot end, and a rear leg having an upper end that is connected pivotally to said handle rod; and a front leg, a handle rod having a pivot end that is connected pivotally to said front leg, and a handle end that is opposite to said pivot end, and a rear leg having an upper end that is connected pivotally to said handle rod; and a foldable connection unit (2, 2') interconnecting said side frame units and including a connecting seat (21, 21'), and two hollow front bottom rods and two hollow rear bottom rods arranged radially around said connecting seat (21, 21'), each of said front and rear bottom rods (22, 23) having a first end (221, 231) that extends into and is connected pivotally to said connecting seat (21, 21'), and a second end (222, 232) that is opposite to said first end (221, 231), said second end of each of said front bottom rods being connected pivotally to said front leg of a respective one of said side frame units, said second end of each of said rear bottom rods being connected pivotally to said rear leg of a respective one of said side frame units; a connecting seat (21, 21'), and two hollow front bottom rods and two hollow rear bottom rods arranged radially around said connecting seat (21, 21'), each of said front and rear bottom rods (22, 23) having a first end (221, 231) that extends into and is connected pivotally to said connecting seat (21, 21'), and a second end (222, 232) that is opposite to said first end (221, 231), said second end of each of said front bottom rods being connected pivotally to said front leg of a respective one of said side frame units, said second end of each of said rear bottom rods being connected pivotally to said rear leg of a respective one of said side frame units; to unfold said stroller frame, said connecting seat (21, 21') being pushed downwardly to a used position so as to drive said second ends (222, 232) of said front and rear bottom rods (22, 23) to move radially away from each other such that said side frame units are driven by said front and rear bottom rods (22, 23) to move away from each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot away from each other and such that said rear leg and said handle rod of each of said side frame units pivot away from each other; and to fold said stroller frame, said connecting seat (21, 21') being pulled upwardly from the used position so as to drive said second ends (222, 232) of said front and rear bottom rods (22, 23) to move radially toward each other such that said side frame units are driven by said front and rear bottom rods (22, 23) to move toward each other in the widthwise direction, such that said front leg and said handle rod of each of said side frame units pivot toward each other and such that said rear leg and said handle rod of each of said side frame units pivot toward each other.