In recent years, 3D display technology has developed rapidly and has been widely applied in fields such as science and technology, education, medicine, military, and entertainment. Currently, most of 3D displays need to wear special glasses for the 3D effect which would cause visual fatigue with long-term use. Therefore, the main direction development of 3D display technology is free stereoscopic display technology which users can see the stereoscopic effect without wearing 3D glasses. Currently, the main naked-eye 3D display methods include: parallax stereoscopy, volumetric stereoscopy, integral imaging display technology, and holographic stereoscopy. The principle of parallax stereoscopy is that the light modulated by optical devices which allows the user's left and right eyes to see two images with parallax and the three-dimensional fusion produces a sense of space and hierarchy to realize the 3D effect. Because the parallax stereoscopy can be laminated with the existing 2D screens with low cost, and can provide better brightness and higher resolution so it is widely used in the field of 3D. At present, the technology of parallax stereoscopy to realize 3D display is mainly cylindrical lens which uses the principle of spectroscopic and refraction of cylindrical lens, so that the light rays of each pixel through the display only enter the left eye and the right eye respectively, so people can see different pictures. However, the cylindrical lens technology still has some drawbacks, such as low brightness uniformity, high crosstalk, low light efficiency, short viewing distance, and the manufacturing is difficulty.Based on the principle of naked eye 3D display and the Fresnel optical theory, this paper designs a Fresnel lens array structure and the star-shaped switch of unit liquid crystal display screen to achieve a four-view naked-eye autostereoscopic 3D display with low-crosstalk and high brightness uniformity (Fig.2). The thickness $ l $ of the Fresnel lens array influences the light intensity distribution curve and the crosstalk (Fig.7). And the structure of the star-shaped switch is designed to reduce the central light intensity of the beam to achieve uniform light intensity distribution, so the center height $ a $ and the center length $ b $ of star-shaped switch also influence the light intensity distribution curve and the crosstalk (Fig.9-Fig.10).Firstly, we simulate and optimize the influence of the thickness $ l $ the Fresnel lens array on crosstalk and the light intensity distribution curve, the simulation results are shown in Fig.7-Fig.8. From the figure, we can see that as the thickness $ l $ increases, the width corresponding to a central light intensity of 0.9 at the viewpoint gradually widens, and the overlapping part between viewpoints becomes smaller. When $ l = 2.772\;{\text{mm}} $, the crosstalk is small. As $ l $ continued to increase, the crosstalk and the width corresponding to the center light intensity of 0.9 at the viewpoint remained essentially unchanged. Therefore $ l = 2.772\;{\text{mm}} $. Then we simulate and optimize the influence of the center height $ a $ and the center length $ b $ which influence the light intensity distribution curve and the crosstalk. As $ a $ decreases, the central light intensity distribution at each viewpoint tends to be flat-topped, and the 0.9 width of light intensity increases (Fig.9). And as $ b $ decreases, the 0.9 width of light intensity decreases and 91% of the viewing area has a crosstalk degree of less than 0.5%. Therefore, when $ a=0.03\;{\text{mm}}$, $ b = 0.04\;{\text{mm}} $, the crosstalk of the star-shaped switch is relatively low.The unit parameters of a 55 in 4K model autostereoscopic 3D displayer are provided and they are optimized by TracePro software. The results show that when the pitch of the Fresnel lens on the exit surface is 0.304 mm, the width of each serration of Fresnel lens is 0.0234 mm, the length of the Fresnel lens is 2.772 mm, and the center height of star-shaped LCD switch is 0.03 mm, center length is 0.04 mm, the width of the star-shaped LCD switch is 0.05 mm, the crosstalk is almost zero on the receiving surface range of 2.5 m, and the problem on the brightness of the image in different positions in improved. In addition, the structure of the Fresnel lens array and the star-shaped LCD switch is simple and easy to manufacture which has significant for achieving a better 3D effect of the naked-eye 3D display.