Coherent light sources in the Deep Ultraviolet (DUV) spectral regions become more important with the development of photolithography, laser micro-machining as well as laser spectroscopy. KBe2BO3F2 (KBBF) is now the only crystal to produce deep-UV coherent light just by using Second Harmonic Generation (SHG). The technical parameter of the SHG, Fourth Harmonic Generation (FHG) and sixth harmonic generation using the Nd:YVO4 laser and the FHG using the Ti:Sapphire laser are obtained according to the frequency doubling in KBBF. The theoretical conversion efficiency of the Gaussian beams was obtained by using the numerical simulation on the crystal KBBF in the matching type I and type II for the first time. These academic results are very useful in DUV-DPL experimental studies.