The invention provides an online detection technology for polarization aberration of a full-field high numerical aperture imaging system. The online detection technology comprises the following steps:designing a series of marking masks with Fourier far-field spectrums and simple structures; characterizing PA of a projection objective in an imaging model by using Jones pupil pseudo-zernike expansion method, and simplifying the imaging model by using the diffraction far-field characteristic of the marking masks; deriving a matrix of imaging light intensity and second-order sensitivity of a PA expansion coefficient according to the discretized imaging model and obtaining the following relationship; carrying out Fourier transform on two sides of a formula and extracting first-order spectral information at the same time to obtain a secondary analysis relation between an imaging result Fourier transform first-order spectrum and the PA expansion coefficient; reasonably changing a polarized lighting mode of a light source, and adjusting parameters such as the position of an integrated mask, an exposure area, imaging off-focus quantity and the like; establishing a second-order overdetermined set according to the obtained relation; finally, reversely solving the PA expansion coefficient of each view field point of a full field by an imaged first-order spectrum, and realizing online detection of full-field PA of the lithographic projection objective.