Angle-resolved scattering, as a typical optical scattering measurement technique, has been widely employed in integrated circuit (IC) manufacturing for high-precision in-line measurement of nanofilm thickness, nanostructure topography parameters, and overlay errors. Its non-destructive nature, high sensitivity, high efficiency, and compact design make it well-suited for these applications. In this study, we developed an angle-resolved polarization scatterometer that integrates ultra-micro-spot polarized illumination with amplitude-division polarization analysis. This system enables single-shot simultaneous acquisition of both real-space and orthogonally polarized frequency-domain images of complex nanostructures within microscopic regions. Since the polarization properties of optical components such as the polarizer, waveplate, and polarization beam splitter significantly constrain measurement accuracy, this study proposes an in-situ stepwise calibration method for system parameters. Based on the principle of extinction ellipsometry, the polarizer azimuth, waveplate retardation and azimuth, polarization beam splitter reflection and transmission ellipsometric parameters, and objective lens orthogonal polarization transmittance were sequentially calibrated with high precision to ensure instrument accuracy. The effectiveness of the proposed calibration method was verified through measurement experiments on standard SiO? thin films and rectangular grating samples. The results indicate that the in-situ calibrated instrument achieved a film thickness measurement repeatability of 0.1 nm, and the grating morphology parameters were in excellent agreement with standard values. This work provides a reliable and accurate in-line measurement method for nano-thin films and nanostructures, supporting process monitoring in advanced IC manufacturing.