Abstract: Aiming at the selection of the working band in the infrared system design, the mid-wave and long-wave infrared were compared and analyzed from several aspects such as detector performance, optical diffusion spot, atmospheric transmission characteristics, target and background radiation characteristics, and sea clutter interference. The detailed test schemes to get the day-night detection effect of mid-wave and long-wave infrared thermal imager were formulated, and a great deal of data of the two detectors at different times and different weathers was obtained.Combined with experimental data and theoretical analysis, the proposal of band selection for infrared system using in remote day and night detection on the other shore was put forward.