Huperzine A loaded microspheres are prepared using a W/O solvent evaporation method. The fixed speed release system is that microspheres composed with thermosensitive methylcellulose based hydrogel. SEM is used to analysis the surface morphology of Huperzine A loaded microspheres, which is shown that the difference of the size of microspheres. The size less than 200µm can be used as injection. Gelation experiment shows that the methylcellulose based solution can be transformed into in-situ hydrogel in 15 minutes at body temperature. The result of in vitro release shows that Huperzine A released in a nearly fixed speed. All the meterials of experiment can be biodegrated completely without operating to remove the gel. This is a promising long-term injection system, which is security and controlable for clinic.