As the integral imaging three-dimensional(3D) display technology is limited by the depth of field in a reconstructed image, it can not be widely used in the fields of 3D display. Therefore, this paper proposes a method to enhance the depth of field in a projection-type integral imaging system based on the angle control. To enhance the depth of field, an additional lens is used to control the diverging angle of every pixel in the elemental image array. Contrast to the conventional method with multi-layers, the proposed method has advantages in simpler systems, higher efficiency and lower requests for display devices. Experimental results show that the depth of field is 6.4 times that of original one when the diverging angle is 1.79°. And as compared to the conventional method with an enhancement of 4 times depth of field, the proposed method has increased by 60% in efficiency. These results demonstrate that the proposed method gives a new way to enhance the image quality for integral imaging display systems.