Abstract: Compared with normal pulsars, millisecond pulsars are a class of neutron stars with faster rotation speed, and the pulse signals emitted by them have extremely high stability. The stability of the polarization profile of pulsars is one of the important issues in the study of pulsar radiation mechanism and interstellar medium properties. The polarization profile stability of three millisecond pulsars PSR J1022+1001, PSR J1730-2304 and PSR J2129-5721 was studied using the observation data of the Parkes 64 m telescope in Australia. Analysis of the observations shows that the polarization profile changes slightly at different times. The reasons for the changes are analyzed and the possible explanations are proposed, including the effect of the interstellar scintillation and the instability of the intrinsic properties of the pulsars.