Abstract: Yellow phosphorus is an important industrial raw material used in pharmaceuticals, food, pesticides, the military, and the chemical industry, significantly impacting the economy. The drying effect is the most important aspect that affects the material properties. Traditional drying methods are often inefficient and energy-intensive, while microwave drying offers unique heating advantages, making it a promising alternative. This paper explores how initial mass, moisture content, and microwave power influence the drying process using microwave technology. The study examined how varying initial mass, moisture content, and microwave power affect the drying characteristics of materials. It calculated the microwave drying efficiency (η) and unit energy consumption (Q_s) under different conditions. Results indicated that increasing the initial mass and moisture content enhances the microwave’s drying efficiency and reduces the unit energy consumption. However, as microwave power increased, the microwave drying efficiency gradually decreased, while the unit energy consumption gradually increased. When the initial mass increased from 20 g to 50 g, drying efficiency rose from 6.58% to 13.12%, while unit energy consumption decreased from 34.33 to 17.20 MJ·kg⁻¹. Similarly, increasing initial moisture content increased from 20% to 40% improved efficiency from 12.36% to 19.15%, unit energy consumption decreased from 14.28 to 11.70 MJ·kg⁻¹. The results showed that the maximum microwave drying efficiency (η) reached 21.51% and the minimum unit energy consumption (Q_s) was 10.99 MJ·kg⁻¹ at a mass of 50 g, a moisture content of 40%, and a microwave power of 360 W. Furthermore, this efficiency and energy consumption were consistent when the initial moisture content ranged from 20% to 40%. Four thin-layer drying kinetic models were used to fit the relevant experimental data, revealing that the Modified Page model was the most suitable for describing the microwave drying process of the material. Surface diffusion coefficients of water molecules were calculated under different conditions, and activation energy was derived from these coefficients. The maximum diffusion coefficient was 1.29 × 10⁻¹⁰ m²·s⁻¹ for an initial mass of 40 g, 1.53 × 10⁻¹⁰ m²·s⁻¹ for an initial moisture content of 30%, and 1.64 × 10⁻¹⁰ m²·s⁻¹ for a microwave power of 900 W. The activation energy was calculated to be 5.95 W·g⁻¹. Using COMSOL, simulations of the electromagnetic and temperature fields under varying microwave power conditions were conducted. The electric field intensity increased with higher microwave power, rising from 8.13 × 10⁴ V·m⁻¹ at 360 W to 1.15 × 10⁵ V·m⁻¹ at 720 W. In the experimental phase, increased microwave power reduces the time required for drying, and the temperature field distribution aligns with experimental results, effectively describing the drying process under microwave influence. This provides a theoretical basis and technical support for the efficient drying of yellow phosphorus-like materials.