This thesis develops an auxetic (negative Poisson’s ratio) piezoelectric energy harvester (APEH) to increase the power output when connecting to an excitation harmonic load. The APEH consists of a piezoelectric element bonded to an auxetic substrate. The auxetic substrate concentrates the stress and strain into the piezoelectric element’s region and introduces auxetic behaviour in the piezoelectric element, both of which increase the electric power output. A finite element model was developed to optimise the design and verify the mechanism of the power increase. Seven auxetic structure designed and characterised. Their performance was compared with each other to recognize suitable structure which has maximum power output. Results show that S-shape structure predicts maximum power output when the APEHs excited by sinusoidal strains peakto- peak of 0.02 mm at the frequency of 100 Hz. Effect of different parameters such as, the thickness of substrate and piezoelectric patch, load resistance, amplitude of excitation, etc are investigated on the values of the energy harvesting of auxetic structure. The obtained results illustrate that increasing the thickness of auxetic substrate and piezoelectric patch increase and decrease the power output of auxetic plate, respectively. Keywords: auxetic piezoelectric energy harvester; Finite element model; S-shape structure