In this research, the influence of pulse width and energy on the nonlinear refractive index (n₂) and nonlinear absorption (β) in Multiwalled carbon- nanotubes (MWCNTs) were experimentally studied. For this purpose, three different MWCNTs concentrations were used and were dispersed in a Polyvinyl alcohol (PVA) solution. We found a highly dependence of n₂ and β with the MWCNTs concentration, optical intensity, and pulse width.