Abstract: Incorporating multi-functional nano-particles into natural fiber reinforced polymer composites can provide with the multi-functionality, making them possess sensor performance, which are capable of in-situ sensing the change of surrounding environment. However, it is realized by dispersing nano-particle into matrix, which normally leads to high viscosity of matrix, hindering its application and meanwhile high nano-particle loadings are needed to reach percolation threshold. Dip coating technology was used for the surface modification of sisal fibres (SF) with multi-walled carbon nanotubes (MWCNTs) dispersion as dye, the resulting MWCNTs modified sisal fibers (MWCNTs-SF) and their epoxy based composite (MWCNTs-SF/EP) sensors were prepared. A continuous and homogenous dispersed MWCNTs network coating forms on surface of MWCNTs-SF. The current versus voltage characteristic curve of MWCNTs-SF indicates the formation of ohmic contacts for MWCNTs-MWCNTs and MWCNTs-electrode. Both MWCNT-SF and MWCNTs-SF/EP are characterized by negative temperature coefficient thermistor. Under external strain-stress, the electrical resistance of MWCNTs-SF and MWCNTs-SF/EP exhibits nearly constant at very low strains, then increases linearly at intermediate strains, while an exponential correlation between electrical resistance and strain exists at higher strains. The different sensing characteristics for MWCNTs-SF and MWCNTs-SF/EP mostly relate to the MWCNTs network structure change during consolidation. The tensile strength of MWCNTs modified sisal fiber fabric reinforced epoxy based composite increases gradually from 37.6 MPa to 46.7 MPa with increasing surface modification time, elastic modulus also increases accordingly.