In our experiment,it was observed that silicon nanocrystal rapidly grows with radiation of electron beam on amorphous silicon film prepared by pulsed laser deposition,and shape of silicon nanocrystal is usually sphere in smaller nanoscale with less radiation time under electron beam,in which the quantum dots are prepared in nanoscale of 2~3nm.In the electron interaction process,it was investigated that the various crystals structures in different orientations form in same time,and condensed structures of silicon nanocrystal are changed with different impurity atoms in silicon film.