Abstract: By employing the sequence pulse counting method (SPCM) anda high sensitive micro load-sensor, a precise and sensitive measurementsystem was established to measure the load-deflection curves of pure Nifoils (purity 99.99%) under three-point micro bending. The wholedeformation field and the applied force were recorded precisely andcompletely. On the basis of the measured curves of the pure Ni foil beamswith various thickness (10 -100um), it is found that the elasticbending rigidity is strongly dependent upon the thickness of the microbeams, that is, an obvious size effect is demonstrated.