A long wave cadmium telluride mercury 1024×768（10 μm） 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 77 K . 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（10 μm） 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.