Abstract: To address the problems of high pH, high salt content, and low soil nutrient effectiveness in light saline-alkali soil in Da'an City, Jilin Province, a pot experiment with rice planting was conducted to investigate the effect of organic fertilizer in ameliorating light soda saline-alkali soil. Three treatments were implemented, i.e. no organic fertilizer as a blank control (CK), ordinary organic fertilizer (M0), and organic fertilizer (M1) prepared with 1% biochar loaded with iron nano-particles (BC-FeNPs). All organic fertilizers were applied at 5% of the soil weight. The results show that compared with CK, the application of organic fertilizer significantly increases the total organic carbon content in light saline-alkali soil by 115%. The M0 and M1 treatments increase the content of iron-bound organic carbon (Fe-OC) by 25% and 175%, respectively. Compared with CK, BC-FeNPs organic fertilizer increases the Fe-OC/TOC ratio from 30.0% to 39.0%while M0 treatment decreases the Fe-OC/TOC ratio. Compared with M0, the addition of BC-FeNPs organic fertilizer significantly enhances the activities of soil invertase, alkaline phosphatase, and catalase. Compared with CK, the addition of BC-FeNPs organic fertilizer significantly increases the richness of soil bacterial communities and the relative abundances of Proteobacteria, Bacteroidota, and Actinobacteriota. The relative abundances of the above-mentioned phyla are positively correlated with soil available nutrient content as well as soil enzyme activities. The organic fertilizer added with 1% BC-FeNPs can significantly increase the total organic carbon content, improve enzyme activity and bacterial community richness by promoting the formation of Fe-OC, thus demonstrating potential for the improvement of saline-alkali soil.