Abstract: The black carbon, which absorbs light intensively, was selected for analysis of relation between effective absorption and Junge index. With increase of Junge index, the absorption coefficient numbers of black carbon firstly descended then ascended, somewhat liked U. For aerosol from the same source, the saving heat capacity of small particles was stronger than large ones. When content of large particles increased gradually, delay time droped correspondingly. Based on optical fiber Michelson interference, transmitting light of reflected light by mirror interfered with reflected light by inner surface of collimator. Phase changed when the interfering light path was illuminated by 1.064 m parallel light. It was recorded that effective absorption of aerosol from sunshine, fog, thin and dense smoke from burned paper using relation between phase variation and effective absorption coefficient, and corresponding sensitivity was 10-6 m-1. The baseline of signal always drifted slowly since environment temperature nearly changed all the time. The foundation was shown for research of absorption process and measurement of absorption coefficient.