The loading curves and Young’s modulus of poly(2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene) (MDMO-PPV) films have been measured using nanoindentation through single- and multicycle- test. The ITO\MDMO-PPV\Al devices were fabricated and measured. We measured the I–V characteristics of the devices under different stresses. We found that the applied stress makes the film not only tightened but also more conductive. The devices showed a good piezoresistive performance. Their piezoresistance coefficients have even reached 4.36 × 10−3 Pa−1. The device resistance significantly decreased with the periodical stress produced by a weight, demonstrating a good sensitivity, stability, and repeatability. We propose that two mechanisms are involved in the I–V characteristics in the bias range from 0 to 4 V. One is the Ohm’s law, which is taking effect at low current density or high stress (more than 118 kPa); the other is the trapped charge limited current (TCLC) mechanism, which is taking effect at high current density and low stress (less than 118 kPa).