A series of self-organized InAs/GaAs quantum dots with spacer layer under different thermal-treat (annealing) temperature and environments were prepared by molecular beam epitaxy. They were investigated by atomic force microscope and temperature-dependent photoluminescence (PL). Results showed that the sample annealed at lower temperature has lager size quantum dots and smaller density of quantum dots. The size of quantum dots is getting smaller and the density of quantum dots is getting larger as the annealing temperature increase. Two broad PL peaks are attributed to the combined size distribution of the bimodal quantum dots.