Abstract: Well dispersed and high crystallized sphere-like ZnSe nanocrystals with diameter of 50-100nm have been synthesized by a microwave-assisted elemental solvothermal method with element Zinc and Selenium as reaction sources,en(en=ethylenediamine) as the chelating reagent,and N₂H₄·H₂O as reductive assistant at 160℃ for 4 hours; The as-synthesized ZnSe nanocrystals were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM).It was found that the shape of ZnSe nanocrystals was controlled by the reaction temperature and time.Through the reaction process and possible mechanism analysis,the results showed that the preferable reaction conditions in which high crystallized sphere-like ZnSe nanocrystals with mean diameter of 60nm could be successfully obtained were using en as the chelating reagent and N₂H₄·H₂O as reductive assistant at 160℃ for 4 hours and sphere-like ZnSe nanocrystals came from the aggregation of ZnSe nanocrystals on the surface of N₂ microbubble.