The aim of this study is the search for new material for the manufacture of wind turbine blades in order to improve its performance and to reduce its cost. A composite material based on hemp natural fibres is studied. A numerical simulation using the finite element method is developed and a comparison of the performances of the new material with the usual composite of carbon fibres and glass is performed. The simulation allows us to calculate the proper values and the Eigenmodes of a wind turbine blade in the rotation. The results showed that the epoxy matrix allows to reduce the weight of composite hemp/epoxy relative to other matrix. It is almost 4.6% lighter than hemp/phenolic and 1.9% that hemp/polyester, so the blades hemp/epoxy has several advantages over the blades hemp/phenolic or over the blades hemp/polyester: this new material is characterised by lower weight and lower cost and has better mechanical features.   Keywords: Eigenmode, proper values, new material, blade, rotation.