The　coupled　equations　of　second　harmonic　generation　of　ultra-short　Pulse　through　a　nonlinear　optical　crystal　CsLiB6O10　is　solved　using　the　Fourier　method.　The　second　harmonic　pumped　by　532　nm,　50　fs　fundamental　wave　through　CsLiB6O10　is　simulated　numerically.　The　results　point　out　that　the　pulse　of　second　harmonic　is　widened　and　the　harmonic　shape　is　deformed　because　of　group　velocity　mismatch　and　group　velocity　dispersion.　The　pulse　of　SHG　is　widened　to　100　fs　and　the　pulse　shaping　of　SHG　is　delayed　to　50　similar　to　60　fs　when　the　CsLiB6O10　crystal　length　is　0.5　mm.