Abstract: A method for preparing bio-active particles by spray drying, liquid nitrogen quick-freezing, and vacuum freeze drying includes the following steps: transporting a feed liquid into a preheated spray tower, wherein the feed liquid forms liquid droplets after being atomized by an atomizer in the spray tower, dispersing air is introduced into a top of the spray tower, and the dispersing air disperses the atomized liquid droplets; introducing hot air into the top of the spray tower, wherein the liquid droplets are partially formed into dry-like particles after being dried by the hot air, the surface dried particles fall, through a bottom of the spray tower, into a cooling pool arranged under the spray tower, and the particles, after being frozen, are transferred to a freeze drying device for freeze drying.