The small spherical α-Fe2O3 particles with uniform size and regular shape were prepared by improved hydrolysis method. The infrared transmisson spectra of this two kinds of particles different in dimension were measured, and all surface modes of small spherical α-Fe2O3 particles were obtained. The effect of aggregation on absorption were discussed, and the two absorption bands in spectra were explained with the approximation of chain aggregation by cylindrical microcrystals. Surface mode theory of multi-atomic cubic particles was generalized and applied to α-Fe2O3 particles in monoaxial crystal structure. The theoretical results of surface mode frequency of α-Fe2O3 particles were presented, which agreed well with those of experiments. The existence of generalized modified LST relation was verified.