Abstract: With the increasing mining depth of coal mines year by year, the safe and efficient extraction of deep coal resources has become a hot issue of current concern. In recent years, microwave radiation has attracted extensive attention in the field of coal mine gas extraction. Microwaves act on coal through thermal and non-thermal effects, and the electric field enhancement effect is an important prerequisite for these two effects. However, current research has not yet clarified the mechanism of electric field enhancement between particles. Existing studies on microwave electric field enhancement rarely involve coal and rock, and even fewer consider the impact of electric field enhancement on temperature changes in coal and rock. Therefore, using COMSOL Multiphysics simulation software, single-particle, double-particle, and multi-particle models were constructed. Considering the characteristic that coal’s dielectric constant changes with temperature, variables such as angle, spacing, loss ratio, particle size, and porosity were controlled to conduct in-depth research on the mechanism of electric field enhancement between coal and rock particles. Results show that the microwave electric field enhancement effect is caused by the combined action of two mechanisms: polarized charge and scattering superposition. When the radius is less than 2 mm, the influence of polarized charge plays a dominant role; when the radius is between 2 mm and 33 mm, polarized charge and scattering superposition act together; when the radius is greater than 33 mm, the influence of scattering superposition becomes dominant. Meanwhile, empirical formulas for the relationship between the electric field strength at the particle center and the spacing-to-diameter ratio, angle, and loss ratio during the polarized charge action stage are given. Furthermore, it is found that the fluctuating electric field distribution of large-sized particles is more conducive to particle temperature rise than the symmetric electric field distribution of small-sized particles, and particles with a certain degree of porosity have a better temperature rise effect. In addition, the temperature change of particles is affected by two factors: internal electric field and dielectric constant. Temperature change is positively correlated with internal electric field change, while internal electric field change is negatively correlated with dielectric constant change.