The microscopic pore structure of a tight sandstone reservoir is highly intricate, presenting challenges in its quantification. The primary focus was on utilizing digital core technology to analyze representative samples extracted from Member 8 of the Lower Permian Shihezi Formation at the Tianshengqiao braided river outcrop in Fugu County, Yulin City, Shaanxi Province.Methods: To achieve the research objectives, eight typical samples were meticulously selected and underwent a series of processes, including image filtering, threshold segmentation, and the maximum sphere equivalent algorithm. Digital representations of the core samples were then processed to establish both three- dimensional pore structure models and ball- stick models. Microscopic structural parameters were calculated to quantitatively characterize the size distribution and connectivity features of pores and throats in tight sandstone reservoirs. The study also incorporated geological assessment methods to complement the quantitative evaluation of the micro- pore structure.Results: The study yielded significant results based on the analysis of pore diameter and throat radius. Pores were systematically categorized into four types (P1 to P4), representing micro, small, medium, and large pores. Similarly, throats were classified into four types (R1 to R4), corresponding to bent sheet- shaped, sheet- shaped, constricted, and pore- narrowing throats. The quantitative evaluation, utilizing parameters such as fractal dimension, shape factor, Euler number, connectivity, apparent porosity, and pore- throat structure type, classified the eight samples into four levels (I, II, III, IV), providing a comprehensive assessment of the micro- pore structure.Conclusion:In conclusion, digital core technology, leveraging its powerful three- dimensional imaging and data processing capabilities, demonstrated effectiveness in accurately and quantitatively characterizing the three- dimensional pore structure in tight sandstone reservoirs. The research outcomes contribute valuable geological insights, establishing a robust foundation for the evaluation and optimization of tight sandstone gas resources.