A protective case for an electronic device with a stretchable display panel , the protective case comprising: a backplate , comprising an accommodating space , wherein the accommodating space is adapted to accommodate the electronic device ; a first housing , comprising a first planar part and slidably disposed on the backplate , wherein the first housing is adapted to abut against a first side of the stretchable display panel ; and a second housing , comprising a second planar part and slidably disposed on the backplate , wherein the second housing is adapted to abut against a second side of the stretchable display panel opposite to the first side , wherein the first housing and the second housing are adapted to move relative to each other to change a distance between the first housing and the second housing , wherein a first sliding part (P1) is disposed on one of the first housing and the backplate at a place on which the first housing and the backplate are adapted to face each other, another one of the first housing and the backplate comprises a first guiding groove (G1), and the first sliding part (P1) is adapted to pass through and slide within the first guiding groove (G1), wherein a second sliding part (P2) is disposed on one of the second housing and the backplate at a place on which the second housing and the backplate are adapted to face each other, another one of the second housing and the backplate comprises a second guiding groove (G2), and the second sliding part (P2) is adapted to pass through and slide within the second guiding groove (G2), wherein the first planar part comprises a first border (E1), the second planar part comprises a second border (E2), the first border (E1) is complementary to the second border (E2) on a plane, and the first planar part and the second planar part are disposed on a side of the backplate (110, 110A, 1 10B) opposite to the accommodating space . a backplate , comprising an accommodating space , wherein the accommodating space is adapted to accommodate the electronic device ; a first housing , comprising a first planar part and slidably disposed on the backplate , wherein the first housing is adapted to abut against a first side of the stretchable display panel ; and a second housing , comprising a second planar part and slidably disposed on the backplate , wherein the second housing is adapted to abut against a second side of the stretchable display panel opposite to the first side , wherein the first housing and the second housing are adapted to move relative to each other to change a distance between the first housing and the second housing , wherein a first sliding part (P1) is disposed on one of the first housing and the backplate at a place on which the first housing and the backplate are adapted to face each other, another one of the first housing and the backplate comprises a first guiding groove (G1), and the first sliding part (P1) is adapted to pass through and slide within the first guiding groove (G1), wherein a second sliding part (P2) is disposed on one of the second housing and the backplate at a place on which the second housing and the backplate are adapted to face each other, another one of the second housing and the backplate comprises a second guiding groove (G2), and the second sliding part (P2) is adapted to pass through and slide within the second guiding groove (G2), wherein the first planar part comprises a first border (E1), the second planar part comprises a second border (E2), the first border (E1) is complementary to the second border (E2) on a plane, and the first planar part and the second planar part are disposed on a side of the backplate (110, 110A, 1 10B) opposite to the accommodating space . <EOS>