As shown in FIG. 8 and FIG. 9, the flexible display screen 3 includes a back film 8, wherein the back film 8 includes a rollable portion 801 and a non-rollable portion 802 connected to each other. The rollable portion 801 can be rolled and can slide out of or into the first housing following the second housing. The non-rollable portion 802 is located at one end of the flexible display screen 3 close to the winding assembly 5 and is connected with the winding assembly. The non-rollable portion 802 does not need to slide out of or into the first housing following the second housing and the non-rollable portion 802 may not be rolled. Modulus of a material of the rollable portion 801 is smaller than that of a material of the non-rollable portion 802, such that when the rollable portion 801 is rolled, strain of a display layer on the rollable portion 801 is small, and the non-rollable portion 802 can be deformed less under the pulling force of the winding assembly, without affecting the function of the display layer on the back film 8.

In an exemplary embodiment, the modulus of the material of the rollable portion 801 is 2 GPa to 5 GPa, and the modulus of the material of the non-rollable portion 802 is 6 GPa to 15 GPa, such that the pulling force of the winding assembly acts on the high-modulus non-rollable portion 802 without affecting the function of the display layer on the back film 8.