The 256×2 HgCdTe focal plane array consists of two 256×1 sub-modules and two photovoltaic silicon readout integrated circuits in parallel and symmetrical configuration.Two different narrowband filters are separately assembled by filter pier.The long wave 256×2 long linear HgCdTe focal plane array is assembled in a metal Dewar.The key technologies of 12.5 μm long linear HgCdTe focal plane array Dewar are solved,which include high accuracy assembly,thermal mismatch design for long linear HgCdTe focal plane array and high reliability package.A series of technologies are used for the suppression of the stray light,the reduction of background radiation and reliability enhancement,which made HgCdTe focal plane array detector performs much better.Some space environmental tests are carried out.Results show that the main performances do not change.The IRFPA detector satisfies the requirements of space application.