Abstract: The first table high power UV ultrashort pulse laser in China is built. The laser energy at 248 nm is amplified from 1 mJ to 50 mJ by discharge pumped KrF excimer laser utilizing off axis amplification technique. The laser pulse width is compressed from 420 fs to 220 fs by compensating the GVD dispersion utilizing prism pair. The diameter of focal spot is 5 μm using a f =40 cm lens, and the power density reaches up to 10 17 W/cm 2.