A 3-D mathematical model of regular wave flume is conducted to investigate the heaving performance of a cylindrical floater. The results show that the transverse velocities near the floater distribute symmetrically at the wave crest and trough times, its symmetry axis is the longitudinal straight line across the floater center, and 4 extreme regions distribute near the floater. With the increase of relative width of wave flume, the trapped wave energy and the relative response amplitude increase firstly. Then, they decreases and appear to be stable for the relative width of wave flume higher than 10. The trapped wave energy and the relative response amplitude increase with the increase of incident wave height, respectively. With the increase of wave period, the trapped wave energy decreases, however, the relative response amplitude increases. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.