Supersaturation in the cloud is the one of key factors affecting cloud macro and microproperties. The Explicit Mixing Parcel Model (EMPM) is used to study the evolution of supersaturation of cloud droplets during the entrainmentmixing process. The results show that in this process, the supersaturation decreases firstly due to the entrained dry air, and then increases due to the evaporation of droplets until the parcel restores new saturation. Then, the effects of different thermal, dynamic and microphysical factors on the reduction of supersaturation and saturation recovery time are analyzed. The sensitive test indicates that the factors of small reduction and quick recovery are the high relative humidity of the entrained dry air and the number concentration of initial cloud droplets. The higher humidity, the less effect of entrainment. The higher the number concentration， the smaller droplet size and the faster evaporation, and thus the supplement to the humidity of dry air is strong. The factor of large reduction and slow recovery is the large fraction of entrained dry air. The more the dry air is entrained, the more evaporation of droplets. The factor of large reduction and quick recovery is the high turbulent kinetic energy dissipation rate. The faster the mixing process, the faster cloud droplets evaporate. The results will help to improve the understanding of the entrainment mixing process and warm cloud precipitation theory.