ICESat-2's advanced topographic laser altimeter system provides unprecedented technical support for polar environmental research including ice sheet mass balance detection and multi-dimensional sea ice parameter retrieval. However, the satellite's technical innovations and application advantages for polar environments still lack systematic elaboration, its high-precision data have not been effectively integrated from single-factor analysis to multi-process collaborative cognition, and the main sources of uncertainty as well as future technical breakthrough paths also remain unclear. To address these gaps, this review explores three core scientific questions. First, how to accurately solve the inversion challenges of key parameters through ICESat-2's technical innovations. Second, how to apply its high-precision inversion results to deepen the understanding of multi-sphere and multi-element interaction processes in polar regions and further reveal their systematic change laws. Third, what are the main uncertainties in ICESat-2's polar monitoring applications and what targeted technical paths can achieve breakthroughs. By systematically organizing relevant research progress, this review clarifies the inherent connection between technical innovations and polar parameter inversion, and ultimately provides solid support for the construction of cross-element integrated scientific cognition of polar environments.