The fabrication and photoluminescence investigation of CdSe quantum dots were presented. The CdSe quantum dots were fabricated by chemical method, and the quantum dots with different radii were obtained by the choice of the reaction time. The photoluminescence method was used to investigate the luminescence properties of the quantum dots both on quartz substrate and in liquor. The researches show that all the samples have good luminescence properties. The electronic states were investigated using a model of spherical square well with infinite depth, and the radii of the quantum dots were estimated from the parameters of the luminescence data. The photoluminescence FWHM (full-width at half maximum) of the quantum dots with different radii shows that the nucleation process takes place at the beginning of the reaction.