By esterification of maleic anhydride (MAH) with flax fiber (LF) C6-OH, LF (LF-g-MAH) containing carboxyl group was prepared and the carboxyl group esterified again with the hydroxyl of hydroxylated multi-wall carbon nanotubes (MWCNT-OH) get the carbon nanotubes (CNTs) chemically grafted LF (LF-g-MAH-MWCNTs) with electrical conductivity and pressure sensing properties. The successful grafting was confirmed by FTIR and EDX. The effects of the grafted carbon nanotubes on the crystallization properties, surface properties, combustion properties and mechanical properties of LFs were studied by XRD, SEM, LOI and stress-strain curves, respectively. The electrical conductivity and pressure sensitivity of the LFs grafted carbon nanotubes were tested. The results show that the grafted carbon nanotubes have no obvious effect on the crystallization properties, surface morphology, combustion properties and mechanical properties of LFs, but making the non-conductive LFs have electrical conductivity and stable and sensitive pressure sensing properties. The pressure sensor can generate a resistance change of 1.0~1.5 kΩ pressed by index finger or generate a resistance change of 10~70 kΩ stepped on by a subject weighing 60 kg to 80 kg.