Because of features such as continuous viewpoints and visual-aid elimination, a integral imaging three-dimensional (3D) display technology has gained widespread acceptance; however, its common phenomenon of visual crosstalk seriously affects the stereoscopic viewing effect. In this study, the effective pixel region of each element image that corresponds to the stereoscopic area was examined, and the corresponding crosstalk-pixel distributions were deduced. Then, a crosstalk-free integral imaging 3D display structure with a full stereo viewing area was proposed, and an accurately designed mask array with a gradient aperture was created. On one hand, the mask array penetrates the effective pixel light, allowing the light to be imaged onto the main view area and all the levels of the stereoscopic view area, thereby retaining all the integral imaging system stereo viewing areas. On the other hand, it blocks the outgoing crosstalk-pixel light, thereby removing crosstalk between adjacent view areas and achieving a complete crosstalk-free integrated imaging 3D display of the full stereoscopic view area. The proposed device is straightforward to build, and it will help popularize the integral imaging 3D display technology.