A flexible display device , comprising: a housing defining a gap and an inner cavity , the gap being in communication with the inner cavity ; a flexible screen component accommodated in the inner cavity and having a stretching end (S2), and the stretching end (S2) extending out of the housing through the gap; and an alarm assembly accommodated in the housing , and the alarm assembly comprising an alarm unit and a detector , the detector being electrically coupled to the alarm unit , the detector being configured to detect a stretched length of the flexible screen component , and the alarm unit being configured to be triggered to raise an alarm when the detector detects that the flexible screen component is stretched to a preset length, characterized in that the flexible display device further comprises a reel located in the inner cavity , the reel being rotatably coupled to the housing , the flexible screen component further having a fixed end (S1) arranged opposite to the stretching end (S2), and the fixed end (S1) is secured to the reel ; the flexible screen component has side edge (S3) coupled between the stretching end (S2) and the fixed end (S1), the side edge (S3) is provided with a limiting portion adjacent to the fixed end (SI); the detector is located outside the reel ; the detector detects a space between the limiting portion and the detector during the stretching of the flexible screen component , to obtain the stretched length of the flexible screen component , and when the flexible screen component is stretched to the preset length, the alarm unit is triggered to raise the alarm. a housing defining a gap and an inner cavity , the gap being in communication with the inner cavity ; a flexible screen component accommodated in the inner cavity and having a stretching end (S2), and the stretching end (S2) extending out of the housing through the gap; and an alarm assembly accommodated in the housing , and the alarm assembly comprising an alarm unit and a detector , the detector being electrically coupled to the alarm unit , the detector being configured to detect a stretched length of the flexible screen component , and the alarm unit being configured to be triggered to raise an alarm when the detector detects that the flexible screen component is stretched to a preset length, characterized in that the flexible display device further comprises a reel located in the inner cavity , the reel being rotatably coupled to the housing , the flexible screen component further having a fixed end (S1) arranged opposite to the stretching end (S2), and the fixed end (S1) is secured to the reel ; the flexible screen component has side edge (S3) coupled between the stretching end (S2) and the fixed end (S1), the side edge (S3) is provided with a limiting portion adjacent to the fixed end (SI); the detector is located outside the reel ; the detector detects a space between the limiting portion and the detector during the stretching of the flexible screen component , to obtain the stretched length of the flexible screen component , and when the flexible screen component is stretched to the preset length, the alarm unit is triggered to raise the alarm. <EOS>