Friction induced vibration (FIV) and its application for energy generation through two-degree-of-freedom (2-DOF) piezoelectric coupled structure are modelled, described, and studied in this work. The FIV mathematical model of 2-DOF system in the direction of friction is established. A 2-DOF energy generator is designed as a sample structure to transform single direction continuum friction motion to high frequency vibration for energy generation. During the operation of a moving plate compressed and sliding on top of the friction excitation module, varying friction force and contact status (sliding and stick) will lead to the dynamic piezoelectric compression deformation, which can generate continuum electrical power for energy absorbing and harvesting applications. Through numerical simulation and parameter studies, the influences of different stiffness ratios, mass ratios, normal force, velocity, acceleration, structure parameter and friction coefficients on the system power generation are analyzed. Through simple structural design, W level power generation can be obtained with few piezoelectric materials. This work revealed the possibility of transforming low frequency excitation to high frequency vibration of general 2-DOF structure for energy generation.