a sealant and a preparation method thereof , a display panel motherboard and a manufacturing method thereof are disclosed . the sealant includes a main adhesive material and a water swellable material dispersed and doped in the main adhesive material . the sealant and the preparation method thereof , the display panel motherboard and the manufacturing method thereof are capable of solving a problem of a notch formed in a sealant where a etchant flows into the display panel unit when the display panel mother board is subjected to a thinning treatment .