Superlens is an imaging device based on metasurface photoregulation. Due to its advantages of miniaturization and process, it has a good application prospect in the aspects of lightweight and portability. In order to meet the demand of lens volume in the current market, a new type of superlens is simulated by using the finite-difference time-domain method. It is a flat plate superlens based on photonic crystal. The size is 2 μm×1 μm, and its working wavelength is in the visible light band of 717 nm. In this design, TiO₂ waveguide was used as the substrate for the plate superlens design. Two groups of Au and GaP photonic crystals with the same period are etched on the TiO₂ waveguide, and the imaging performance of the lens is simulated and studied. In addition, by introducing a series of defects with different shapes, the imaging performance of the plate lens is analyzed. The results show that when the defect structure is a rectangular size of Lx=0.5 μm, Ly=0.8 μm, the plate superlens presents the best imaging performance and reaches the value of 0.556λ super-resolution, which greatly improves the imaging quality. The flat superlens has great potential in portable imaging devices, AR, VR, and small medical devices in the future.