MEPCMS (Microencapsulated Phase Change Material Slurry) is a latent heat functional thermal fluid that combines heat storage, temperature control, and heat transfer enhancement. It holds significant potential for cooling small devices with high heat flux. To better reveal reality, a modified discrete phase model (DPM) based on Euler-Lagrange method was employed to simulate the flow and heat transfer of MEPCMS in the rectangular minichannel through considering the volume concentration of particles. The results reveal that the modified DPM can effectively predict pressure drop, and the maximum error is less 5.54 %. In the fluid-particle forces, the drag force has the greatest impact, and the thermophoretic force takes second place. The heat transfer is enhanced when the particles near the wall undergo phase transition, and the Nusselt number (Nux) reaches a maximum value when the particles near the wall finish the phase transition. Additionally, the work explores the effects of inlet flow velocity (v), inlet temperature (Tin), and particle concentration (cm) on the flow and heat transfer of MEPCMS. Only cm affects the peak value of Nux, in comparison to the base liquid, under the condition where the Tin = 288.15 K, v = 0.1 m·s−1 and cm = 10 %, the maximum value of Nux has been enhanced by 12.27 %. Under the conditions of Tin = 293.15 K, cm = 10 %, and v = 0.10 m·s−1, MEPCMS experiences a maximum increase of 24.07 % in pressure drop compared to the pure basic solution. By introducing the comprehensive performance evaluation factor η, it is found that, under conditions of Tin = 293.15 K, v = 0.20 m·s−1, and cm = 10 %, the mean Nusselt number of MEPCMS can be enhanced by 7.56 %, while the temperature difference at the bottom wall is reduced by 24.61 %, while maintaining η at 1.014.