The invention discloses an 
asenapine slow-release 
microsphere agent and a preparation method thereof. The 
microsphere agent is prepared from 
asenapine or salts and polyesters thereof, wherein the weight percentage of the 
asenapine or salts thereof counted by asenapine is 5-50%, and the weight percentage of the polyesters is 50-95%. The preparation method comprises the following steps: (1) conducting weighing; (2) adding the 
polyester material into an 
organic solvent for completely dissolving the 
polyester material to obtain a settled solution, then dissolving or suspending the 
medicine asenapine or the salts thereof into the settled solution to be used as an 
oil phase; stirring or shearing the 
oil phase at high speed to form a homogeneous 
oil phase; and in case of need, adding a right amount of acid for salifying the asenapine; and (3) preparing the 
microsphere agent by a microdroplet generating device, or a 
spray drying method, or an atomizing extraction method. The microsphere agent provided by the invention has relatively high production efficiency, the D50 particle sizes of the prepared microspheres are all below 80mu m, are controllable and are concentrated in distribution, the 
drug-
loading rate is as high as 45%, and the encapsulation rate is above 85%.