A flexible display substrate, a method for manufacturing the same and a flexible display motherboard are provided in the present disclosure. The flexible display motherboard includes a carrier substrate, a separation layer provided above the carrier substrate, a deformable layer covering the separation layer, a flexible substrate provided above the deformable layer, and a display device provided on the flexible substrate, wherein the deformable layer shrinks and deforms under a preset triggering condition to separate the flexible substrate from the carrier substrate without any damage to the display element, and the light-outgoing effect of the flexible display device can be improved.