The main advantage of an integral imaging system is that it does not cause a vergence-accommodation conflict to the viewer, as happens in other types of three-dimensional (3D) display systems. However, it still has the disadvantage of having a limited depth range. In this Letter, the fabrication of the electrowetting liquid lens array with an adjustable focal length is presented. With the liquid microlens array, we propose a focus tunable integral imaging system having an enhanced expressible depth range. The fabricated lens array has 1 mm lens pitch, 100 mu m sidewall, 20 x 14 mm total size, -542 to -89 D focus variability, and 11.6 ms response time. The fabrication process, a measurement of optical characteristics, and a demonstration of the focus tunable integral imaging system are presented in this Letter.