Abstract: Atom lens generated by a laser standing wave can be used to focus an atomic beam to nanometer dimensions. Aberrations exist in atom lens owing to the influence of velocity spread, beam spread, wave nature of atoms and so on. Two theoretical models were built to describe atom lens. Spherical aberration, chromatic aberration and the aberration caused by angular spread were analyzed with semiclassical model, and diffractive aberration was analyzed using quantum model. Simulation results show that aberration originates mainly from beam spread, and diffractive aberration is larger than spherical aberration and chromatic aberration. Three solutions of optimization of experimental parameters, adding beam mask and using etching technologies for improving atom lithography quality are presented.