PbS quantum dots with HMDS ligands were prepared in liquid colloidal phase. Change of electroptical band gap sizes resulting from different particle sizes could be confirmed by the absorption peak shifts in UV/VIS and IR spectra. Particle sizes were controlled with the same materials under the same reaction conditions but reaction vessel temperature between 100 and 160℃. The absorption peaks were observed at 800~1200nm and the shift magnitude showed a linear relation with the reaction temperatures.