A long wave cadmium telluride mercury 1024×768(10μm) focal plane detector assembly was prepared by arsenic ion implantation p-on-n planar junction technology. The cutoff wavelength of the device is 9.61 μm at 77K . The basic performance of the detector assembly was characterized under half well filling level condition, and the results showed that the non-uniformity of the responsivity was 4.15%, the average NETD was 28.5mK, and the operability was 99.81%. A dedicated metal micro-structure was designed and prepared on the surface of a LW MCT 1024×768(10μm) focal plane detector chip set, and the crosstalk between pixels was characterized and analyzed. The results showed that device crosstalk was 12.3%, and the MTF was 0.35. Finally, imaging demonstrations of outdoor scene and indoor person were conducted with the detector assembly, both of which showed good imaging effect.