Abstract: A dual-band slot antenna array for submillimeter-wave imaging is designed and optimized in this study. The antenna array can be integrated on the submillimeter-wave imaging chip to realize the signal reception and frequency selecting. The slot antenna array effectively constrains the radiation direction which matches the optical path of the imaging system, thus improving the optical efficiency. This design not only simplifies the optical path, but also effectively reduces the noise and improves the sensitivity of the system. The bandwidth of the dual-band antenna covers the center frequency of 230 GHz and 350 GHz, two common detection windows of submillimeter wave. The feed network is composed by impedance tapering microstrip lines to meet the impedance matching on two broadband windows. The maximum gain, the main lobe width, the sidelobe suppression of the 8×8 slot antenna array are 15.3 dBi, 21.1^\circ, −11.4 dB at 230 GHz, and 15.5 dBi, 18.7^\circ, −13.5 dB at 350 GHz, respectively, which has the characteristics of high gain and low sidelobe, and the main lobe is matched with the optical path of the imaging system. To confirm this design concept, 15 GHz and 23 GHz slot antenna units and arrays are fabricated and measured in the microwave band. The measured results are in good agreement with the simulated results, which validates the feasibility of the on-chip dual-band slot antenna array for submillimeter-wave imaging.