Abstract: In heterogeneous reservoirs with high water consumption bands, the effect of single flooding technique after multi-phase flooding is getting worse and worse, and the combination of bulk particle and gel flooding has potential.The study of the micro-mechanism of the combination of bulk particle and gel is of great importance to reservoir adaptability and parameter optimization.The relationship between permeability and pore throat size was determined through the combination of mercury injection curves and nuclear magnetic resonance T₂ spectra, leading to the establishment of a corresponding microscopic displacement model. Microfluidic experiments and visual glass chip models were employed to directly observe the microscopic blocking mechanisms of bulk particles and gels. The bulk particle size corresponding to the actual pore throat size was evaluated based on injection capacity. Based on these observations, the injection parameters of bulk expanded particles and gels were evaluated and optimized using longitudinal and planar heterogeneity models.When the bulk expansion particle diameter to pore throat diameter ratio (BTR) was less than 1.0, injection was more effective. However, when the BTR exceeded 2.0, injection became difficult. Larger particles entering the pore throat exhibited greater strength post-expansion, resulting in better plugging properties. The injection effect was optimal with a higher proportion of bulk slug (0.7 PV) and a lower proportion of gel slug (0.3 PV). Compared to pure gel or bulk slug, the recovery rate increased by 20.1%. The combination of glue and bulk expansion particles can improve oil recovery by plugging heterogeneous reservoirs dominated by large pores.