A foldable display module and its formation method, and a foldable display device are provided in the present disclosure. The module includes a foldable display panel and a support plate which are disposed oppositely. The support plate includes a first support part and a second support part; the first support part is made of a first material; and the second support part is made of a second material; the foldable display module includes a bendable region and a non-bendable region; the foldable display panel includes a bendable portion and a non-bendable portion; the bendable portion is at the bendable region; and the non-bendable portion is at the non-bendable region; the first support part includes a first portion configured to support the bendable portion of the foldable display panel; and the second support part is configured to support the non-bendable portion of the foldable display panel.