Silicon columns are arranged periodically to constitute a photonic crystal slab with hexagonal structure in the air medium, and different configurations of defects are introduced in the photonic crystal slab. The effects on imaging quality are mainly discussed by changing the radius of the defect dielectric column and the center position of defects. Through the method of finite difference time domain, simulation results show that the change of dielectric column radius and the position of defects can increase the transmittance of light and enhance the image intensity. Due to the introduction of defects, the interference between the defects can reduce the resolution of the imaging.