The semi-permeable layer is defined as the ability of seeds to allow water uptake and gas exchange while at the same time restricting or preventing solute diffusion which occurred in some plant species.The location of a semi-permeable layer is in the seed coat or endosperm.The chemical nature of this layer is cellulose,cutin,suberin or callose and is formed during the process of the seeds development.The site and chemical composition of this layer have the diversity of species.The important value of this layer in seed development,germination and seed vigour test are discussed.This paper reviews research on the characterization,location,chemical composition and research methods of the seed semi-permeable layer and some suggestions have been made for future research work.