Abstract: Magnetars are a type of neutron star with extremely strong magnetic fields ranging from 10¹⁰～10¹¹ T, which are significantly different from the properties of ordinary pulsars. They are generally associated with supernova remnants and exhibit strong activity, making them important objects for studying extreme astrophysical properties and corresponding to one type of Fast Radio Burst (FRB). The magnetic structure and the origin of the activity energy of magnetars have always been central issues in magnetar research, and thus, polarization observation information is crucial for understanding their nature. Since the launch of the Imaging X-ray Polarimetry Explorer (IXPE), in-depth observations have been conducted on four magnetars: 4U 0142+61, SGR 1806-20, 1RXS J170849.0-400910, and 1E 2259+586, marking a deepened study of their properties. This includes the verification and limitation of the magnetar polarization model. This article summarizes the observational results of these four magnetars and discusses the findings in relation to the main magnetar models, which are the rotating vector model, the resonant Compton model, and the vacuum resonance model.