A garbage can lid having garbage compressing mechanism, including: a main body, adapted for being disposed on a can above a can opening of the can, the main body being formed with an opening; a pivoting lid, pivotally disposed on the main body to selectively close the opening, the pivoting lid being formed with a through hole; a pressing pad, arranged below the pivoting lid, a face of the pressing pad facing the pivoting lid having a connecting portion which positionally corresponds to the through hole; a restoring element, associating the pivoting lid and the pressing pad so that the pressing pad tends to move toward the pivoting lid; a pressing rod, the pressing rod having a pressing element and an engaging portion at two opposite ends thereof, the engaging portion being able to be inserted through the through hole of the pivoting lid to be detachably engaged with the connecting portion of the pressing pad so as to push the pressing pad downward, characterized in, that a top of the pivoting lid is recessedly formed with a receiving room, the through hole is formed on a bottom of the receiving room, a top lid is disposed on the pivoting lid to selectively cover the receiving room, the pressing rod includes four rod segments which are pivotally linked one by one so that the pressing rod is foldable to be received in the receiving room, a restriction structure is arranged between any two adjacent rod segments, the restriction structure includes a restriction notch and a restriction protrusion which has an inclined top face, the restriction notch is formed on one of the two adjacent rod segments, the restriction protrusion is formed on an outer surface or the other one of the two adjacent rod segments, the restriction protrusion is covered by its adjacent rod segment and the restriction notch and the restriction protrusion are staggered from each other when the two adjacent rod segments are aligned, the restriction protrusion is received in the restriction notch to prohibit the two adjacent rod segments from pivoting with respect to each other when the two adjacent rod segments are substantially perpendicular to each other, the pressing element is pivotally disposed on a free end of the most distal rod segment, the restriction structures allow the four rod segments to pivot to form a rectangular frame, the rectangular fame is able to be received in the receiving room. a main body, adapted for being disposed on a can above a can opening of the can, the main body being formed with an opening; a pivoting lid, pivotally disposed on the main body to selectively close the opening, the pivoting lid being formed with a through hole; a pressing pad, arranged below the pivoting lid, a face of the pressing pad facing the pivoting lid having a connecting portion which positionally corresponds to the through hole; a restoring element, associating the pivoting lid and the pressing pad so that the pressing pad tends to move toward the pivoting lid; a pressing rod, the pressing rod having a pressing element and an engaging portion at two opposite ends thereof, the engaging portion being able to be inserted through the through hole of the pivoting lid to be detachably engaged with the connecting portion of the pressing pad so as to push the pressing pad downward, characterized in, that a top of the pivoting lid is recessedly formed with a receiving room, the through hole is formed on a bottom of the receiving room, a top lid is disposed on the pivoting lid to selectively cover the receiving room, the pressing rod includes four rod segments which are pivotally linked one by one so that the pressing rod is foldable to be received in the receiving room, a restriction structure is arranged between any two adjacent rod segments, the restriction structure includes a restriction notch and a restriction protrusion which has an inclined top face, the restriction notch is formed on one of the two adjacent rod segments, the restriction protrusion is formed on an outer surface or the other one of the two adjacent rod segments, the restriction protrusion is covered by its adjacent rod segment and the restriction notch and the restriction protrusion are staggered from each other when the two adjacent rod segments are aligned, the restriction protrusion is received in the restriction notch to prohibit the two adjacent rod segments from pivoting with respect to each other when the two adjacent rod segments are substantially perpendicular to each other, the pressing element is pivotally disposed on a free end of the most distal rod segment, the restriction structures allow the four rod segments to pivot to form a rectangular frame, the rectangular fame is able to be received in the receiving room.