In this paper, a new structure of horizontal parallax light field 3D floating image display system was proposed. The structure consists of pico-projectors, Fresnel lens, micro-lens array and sub-lens array with freeform shape. By the functions of optical components, each light field of projectors could be controlled as a fan ray, which has high directivity in horizontal and wide scattered angle in vertical. Furthermore, according to the reverse light tracing and integral image display technique, horizontal parallax floating 3D could be demonstrated in the system. Simulated results show that the proposed 3D display structure has a good image quality and the crosstalk is also limited below 22.9%. Compared with other 3D technologies, this structure could have more benefits, including displaying real high resolution floating image, unnecessary of physical hardware on the image plane, scalability of large size system, without the noise from spinning component, and so on.