The last decades have been marked by an increase of environmental awareness concerning the use of composite materials made from fossil resources. Therefore, many works have been carried out to promote the use of bio-based composite made from renewable resources. Natural fibres can be used as reinforcement and have the advantages to be cost-effective. These materials also offer higher mechanical properties compared to the synthetic ones. However, their original surface properties usually lead to a lack of interfacial adhesion between the surfaces when embedded into a polymeric matrix. In addition, natural hydrophilicity of the natural fabrics strongly affects the manufacturing process for the composite reducing his long-term stability (i.e. delamination of the layers). For these reasons, the use of fibres made from renewable resources remains today limited to a small number of applications in the industry. In this work, an alternative dry-wet method is used to modify the surface proprieties of flax fibres. The composite consists of alternating layers of treated flax fabric and poly lactic acid (PLA) sheets. The latter was chosen because its low environmental and economic impact as well its bio-based and biodegradable properties. Initially, fibres were treated with a dry-wet method prior the thermo-compression process to induce better chemical interactions with the polymer matrix. Dry plasma treatment (dielectric barrier discharge) and classical wet acetone modifications were employed to increase the chemical attachment of lignin to the surface of the fibres. FTIR, XRD, and XPS tests were applied to study the impact of the treatments on the surface properties. Then, to evaluate the improvements induced by our functionalization method, the final composite materials have been subject to a tensile test.