The distributions of the chemical states of131I,132I,133I,134I and135I produced by the spontaneous fission of252Cf were investigated by the method of fractional precipitation separation in 6M NH4OH solution followed by measurement of the X-ray spectrum of the samples with a Ge(Li) detector. The iodine fission fragments were separately collected in the matrices of NaNO3, NaCl, dehydrated sodium sulfate, CH3COONa·3H2O, Na3H2IO6, KI and NaIO3 crystals. The results showed that the distribution of the chemical states was the function of the collection time, the nature of matrix materials and the type of iodine isotopes. The relative amount of the reduced states of134I decreased with the increase of collection time in the matrix of NaNO3. The ratio of the amount of reduced states to the total amount of the134I was the highest (50.4%) in NaCl matrix and the lowest (9.4%) in Na3H2IO6 matrix. The relative quantities of reduced states of135I were the highest (58.5% and 97.7%) and that of134I were the lowest (16.9% and 63.1%) in matrices of NaNO3 and NaCl, respectively.