A floating energy harvester using the piezoelectric effect is developed to harvest the energy from intermediate and deep water waves. The harvester is made of a mass-spring system used for transferring wave motions to mechanical vibrations and two piezoelectricity-lever devices used for amplifying and transferring the collected mechanical vibration to electrical power. A mathematic model is established based on the Lagrangian-Euler method and solved by the iteration method to calculate the root mean square value of the generated electric power. The harvested power is found to increase with an increase in the ocean wave amplitude, mass of the mass-spring system, sizes and Young's modulus of the lever, and a decrease in the ocean wave period. The results show that a power up to 103 W can be harvested for a practical floating energy harvester with a width, height, length, mass of the mass-spring system of 1 m, 0.5 m, 1 m, 100 kg, and an amplitude and period of a sea wave of 2 m and 6 s, respectively. (C) 2016 Elsevier Ltd. All rights reserved.