Abstract: The connected defective elements identifications has always been the research difficulty of focal plane array (FPA) detector. It is difficult to identify connected defective elements by FPA test-bench because the response voltage of connected defective elements is basically the same as that of normal elements. Novel optical filter for connected defective elements identifications was proposed. The presented filter had sorted elements of FPA detector into two kinds of detection units. The two kinds of detection units were designed in pairs and staggered arrangement closed to each other. The response voltage of the connected defective elements was 50% of that of normal elements. The connected defective elements were identified markedly by using the proposed filter.