This　paper　introduces　the　principles　of　intelligent　microcurrent　measurement　instrument.　And　then　proceeding　from　raising　the　accuracy　of　the　measurement　and　from　the　automation,　a　combination　-　way　current　-　-　voltage　conversion　unit　having　the　stability　and　the　precision　is　devised　emphatically.　The　unit　is　being　controlled　by　microcomputer　and　the　wide　range　automatic　search/conversion　can　be　realized.　This　instrument　can　accurately　measure　the　microcurrent　over　10(-12)A　similar　to　10(-5)A,　the　error　being　less　than　2%　for　10(-11)A.