Detection in ultraviolet and infrared ranges is essential for remote atmospheric sounding which includes important information closely related to human life. Based on finite difference time domain method (FDTD) and finite element method (FEM), the mechanism of Pt/CdS and InSb ultraviolet-infrared dual-color focal-plane arrays are investigated. It is found that a high ultraviolet photo response can be achieved for Pt/CdS Schottky junction under an ultrathin Pt top contact. Further simulations show that the ultrathin top contact can efficiently couple the infrared radiation for the dual-color focal-plane arrays detector. The center to center spacing of each pixel of 50μm in the ultraviolet and infrared dual-color focal-plane arrays detector based on Pt/CdS and InSb junctions can significantly reduce crosstalk. Our work provides fundamental guidance for optimization and design of ultraviolet and infrared dual-color detector.