In order to study the characterizations of different metal nanoparticles colloids produced by laser ablation,under optimized ablation conditions,the Ag,Au and Ti nanoparticles colloids are prepared and analysed. The measurement results of UV-vis and transmission electron microscope (TEM) show that the Au nanoparticles are of the best characterizations. the average diameter is the smallest,the distribution of particle size is the narrowest and the morphologies are homogeneous. The mechanism of the results is not yet clear and is the subject of further investigations.