Abstract: The structure of soil pores is a critical determinant of various soil functions, including water infiltration and retention, soil permeability, nutrient availability, and aeration and mechanical impedance to root elongation. The dynamic behavior of soil pores is primarily influenced by tillage practices, the presence of crop roots, and the return of soil organic matter. This research endeavor sought to investigate the impacts of prolonged applications of organic fertilizers and straw on soil pore structure, as well as to elucidate the relationship between soil organic carbon and soil pore structure. The study utilized data from a 16-year long-term field experiment located in Shui Tou agricultural experimental base, Shanxi Agricultural University (Shanxi Academy of Agricultural Sciences), Yuncheng, Shanxi Province, comprising four distinct treatments: sole chemical fertilizer (F), organic fertilizer + chemical fertilizer (MF), straw returning + chemical fertilizer (SF), and organic fertilizer + straw returning + chemical fertilizer (MSF). The soil pore structure was examined using X-ray computed tomography (CT) and advanced image processing, while the soil organic carbon and its physical fraction contents (free particulate organic matter (FPOM), occluded particulate organic matter (OPOM), and mineral-associated organic matter (MOM)), were assessed. Additionally, the structural characteristics of the organic carbon were qualitatively and quantitatively analyzed by Fourier transform infrared (FTIR) spectroscopy. The results indicated that all organic amendment treatments significantly enhanced the total porosity and porosity of >0.5 mm aperture compared to the F treatment (P<0.05). Notably, the MSF treatment exhibited the highest values, increasing total porosity and porosity of >0.5 mm aperture by 61.6% and 66.2%, 23.0% and 31.1%, and 16.8% and 13.5% relative to the F, MF, and SF treatments, respectively. Additionally, the porosity ranging from 0.5 to 0.2 mm in the MF and MSF treatments was significantly higher than that in the F treatment (P<0.05). However, there were no significant differences in porosity ranging from 0.2 to 0.06 mm among all treatments. The MSF treatment resulted in a statistically significant enhancement in the connectivity and complexity of soil pores, with increases of 33.2% and 17.9%, respectively, in comparison to the F treatment (P<0.05). In comparison to the F treatment, the organic fertilizer and straw returning treatments (SF, MF, and MSF) resulted in a significant increase (P<0.05) in the contents of total soil organic carbon, FPOM, OPOM, and MOM. Among these treatments, MSF exhibited the highest values, with concentrations of 21.5 g/kg, 7.1 g/kg, 4.2 g/kg, and 10.2 g/kg, respectively. The long-term straw incorporation and the application of organic fertilizers (MSF) were advantageous for the accumulation of polysaccharide and lipid organic carbon in the soil, while concurrently reducing the content of aromatic organic carbon. The Pearson correlation analysis revealed a positive and significant relationship between soil total porosity, porosity of >0.5 mm aperture, and the connectivity and complexity of soil pores with the contents of total soil organic carbon, FPOM, OPOM, MOM, and polysaccharide and lipid organic carbon (P<0.05). These findings suggested that the application of organic fertilizer and straw incorporation can enhance soil organic carbon content and promote the accumulation of polysaccharide and lipid organic carbon, which facilitated the formation of soil pores and improved soil pore structure. Consequently, the enhanced physical properties of the soil were attributed to the regulation of soil structure by the organic amendment, which facilitated an optimal distribution of soil pores, increased soil complexity, and improved pore connectivity. Accordingly, the organic amendment may be considered an effective strategy for optimizing soil pore structure. Future studies should also examine the response of soil pore structure and pore size distribution to the decomposition of incorporated organic manure.