A flexible AMOLED substrate and a manufacturing method thereof are provided. The method includes: forming a flexible backing, which includes a display section and a bending section disposed on an outer circumference of the display section; forming a buffer layer on the flexible backing, removing a portion of the buffer layer that is disposed on the bending section and preserving a portion of the buffer layer that is disposed on the display section so that an inorganic insulation layer on the bending section has a reduced thickness to improve bending resistance of the bending section of the flexible AMOLED substrate and thus improving production yield. The flexible AMOLED substrate is manufactured with the above method, in which an inorganic insulation layer included in a bending section has a reduced thickness so that the bending section of the flexible AMOLED substrate shows better resistance against bending and provides high production yield.