Photon sieves were successfully designed after patterns optimization, and the focusing ability of 355 nm laser was investigated and compared with traditional Fresnel zone plates through experiments. Firstly, optimal patterns of photon sieves were automatically generated by the macro program. Secondly, photon sieves and zone plates with 2 μm critical dimension were fabricated for focusing 355 nm lasers. Finally, with focusing-spot testing system, the focusing spot of 355 nm laser was gained for photon sieves and zone plates, and diameters of focusing spots were measured. The experimental results indicate that photon sieves have promising ability to achieve finer focusing spot and suppress more side lobe than zone plates.