Nonlinear refractive index(n2),absorption coefficient(β) are material figures of merit for ultrafast all-optical switch.n2 and β of GeS2-Ga2S3-Sb2S3-AgCl glass were measured by using Z-scan technique .The result shows GeS2-Ga2S3-Sb2S3-AgCl glass is characteristic with high value n2(1.581×10-10esu),little β at 800 nm(β=4.707cm/GW).The nonlinearity is attributed to high polarization of cation in the glass.