Recently, nuclear magnetic resonance (NMR) technology has been widely used in the field of oil and gas exploration and exploitation. T2 cutoff value (T2c), as a core parameter in NMR analysis, is critical to understanding pore structure characteristics, fluid types, and their mobility. In this paper, calculation methods of T2c and its application in pore structure characterization are reviewed. The future development directions of T2c in the field of oil and gas are also discussed. Firstly, the basic principle of NMR is introduced. The T2 spectrum displays the signal intensity at different relaxation times, thereby allowing the analysis of the sample’s pore structure. Secondly, the methods for determining T2c are summarized. Methods for determining T2c can be divided into the single T2c value method and dual T2c values method. The dual T2c values method can be further divided into the observation method and experimental method. They differ in their accuracy in characterizing fluid flow characteristics. Thirdly, the current applications of T2c in characterizing pore structure, including mobility, porosity, permeability, pore size distribution and fractal dimension, are summarized. T2c allows for a more accurate assessment of fluid mobility and productivity potential in the reservoir. Finally, the future of T2c research is prospected. With the improvement of computing power and data processing algorithm, the evaluation of oil and gas reservoir based on T2c will be more refined and personalized.