The invention discloses an expandable mobile phone cover, comprising a mobile phone cover body and an expanding lens. A camera through hole is arranged on the mobile phone cover body. A clamping hook is arranged on the expanding lens. A hooking part is arranged on the mobile phone cover body. The expanding lens and the mobile phone cover body can be hooked together. The expanding lens and the mobile phone cover body are connected, so that the expanding lens covers the camera through hole. When the mobile phone cover is used, a camera of a mobile phone is located at the inner side of the camera through hole, the expanding lens is located at the outer side of the camera through hole, in this way, the lens is increased for the camera of the mobile phone, and functions of the mobile phone are further expanded. The mobile phone cover is applied to the mobile phone.