The use of natural fibres as composite reinforcements is inevitable in view of developing a sustainable environment. When a natural fibre is extracted from a plant or ground or animal, they are prone to contain impurities and other unwanted substances. By removing these unwanted substances and by enhancing the strengths of the fibres, the reinforcements become predominant to carry the loads in a composite material and thus help the composite to acquire major mechanical properties. Hence, pretreatment methods are adopted for green fibres and it includes a series of chemical treatment, drying, heating in a furnace, and so on. These treatments help to enhance the surface roughness of the fibre, and thus, it increases the bonding strength with the surrounding matrix. The present study gives a clear picture of various pretreatment methods made in different research and their effect on the properties of the composite materials.