The　pulse　expansion　and　deformation　caused　by　group　velocity　dispersion　in　optical　parametric　effect　of　the　negative　uniaxial　crystal　CsLiB6O10　are　studied,　by　momentum　conservation　and　coupling　wave　equations.　The　numerical　results　show　that,　under　the　conditions　of　hyperbola　secant　wave　form,　no　chirp　modulation,　pulse　width　of　50　fs　and　crystal　length　of　10　nm,　the　pulse　expansion　caused　by　group　velocity　dispersion　for　incident　wavelength　of　532　nm　is　1.6　times　of　that　for　wavelength　of　213　nm.　The　pulse　expansion　is　related　to　the　incident　light　wavelength　and　crystal　length,　and　the　pulse　expansion　and　deformation　are　more　severe　for　shorter　wavelength　and　crystal　length.　The　wave　form　symmetry　is　destroyed　and　the　side　band　phenomena　is　also　introduced　by　the　pulse　expansion.