Samples of GaAs implanted with tin were irradiated with a Q-switohed ruby laser (-1J/cm2, 30-40 ns). Investigation on proton channeling and electron diffraction showed that the amorphous layer of samples implanted with 60 keV or 300 keV Sn ions was recrystallized by laser irradiation, and the dopant atoms were in substitutional sites. The maximim concentration of GaAs carriers was up to 1×1019/cm3 after annealing, it is 20 times higher than that of the heat annealed samples.