The microenvironment change of macromolecular chains of pH/temperature dually responsive microgels with interpenetrating polymer network（IPN） structure,based on poly（N isopropylacrylamide） （PNIPA） network and poly（acrylic acid） （PAA） network in D2O dispersion during their phase transition,were investigated by Fourier transform infrared（FTIR） spectra and IR difference spectra at different temperatures and pH values.With the increase of pH value of D2O,the intensity of the symmetric C‖O stretch IR band from carboxylate anions（1 568 cm-1） was increased,and the intensity of the C‖O stretch band from COOH groups（1 705 cm-1） was decreased,which indicated that the COOH groups of PAA chains in the microgels dissociated into COO-leading to the phase transition induced by pH variation.However,IR bands of main characteristic peaks of PNIPA were hardly changed,which indicated the microenvironment of PNIPA chains was not evidently changed with the pH variation,and the PNIPA network within the microgels holds relative independence.The appearance of both positive peak（1 650 cm-1 and 1 448 cm-1） and negative peak（1 625 cm-1 and 1 479 cm-1） with the redshift of the amide Ⅱ bands and the blueshift of the amideⅠ bands of PNIPA component after temperature induced phase transition of the microgels exhibited that the hydrogen bonds between amide groups and waters were damaged,and the number of free amide groups were increased.In addition,the appearances of both positive peak（2 970 cm-1） and negative peak（2 990 cm-1） with redshift of the C—H stretching bands for the isopropyl groups of PNIPA component may be due to breakdown of water cage structure around the groups.