Abstract: FTIR was applied to the research on effect of temperature on C-H stretching region , molecular conformation and intermolecular force of stearic acid. FTIR, second derivative FTIR, four derivative FTIR and deconvolution FTIR spectra of C-H in the temperature range of 293-393 K was obtained by temperature-control IRS technology. It was found that ① there were two weak distinct bands occuring at approximately 2 965, 2 870 cm-1 at the temperature 293-333 K in the FTIR spectrum; the first band was asymmetrical stretching mode νas(-CH3), and the second band was symmetrical stretching mode νs(-CH3); derivative FTIR spectra and deconvolution FTIR spectrum could increase FTIR spectral resolution; ② the ether in the hydrocarbon chain of stearic acid was packed in parallel direction trans conformation at the temperature 293-333 K and the organized structure was disrupted at the temperature 348-353 K; ③ the intermolecular force of stearic acid decreased gradually with increasing temperature.