Higher order nonlinear susceptibilities of the cyanine dye PC films on the silica substrates deposited by spin-coating technique,are investigated by means of the laser-induced transient grating(TG)technique. The third-order nonlinear susceptibilities are measured to be 20.5 ×10^－13esu～30.3 ×10^－13esu,and the response times are 59～102 ps at different concentrations. Their nonlinear response can be due to the conjugate π electronics of the pentamethine chain. The results show that the laser-induced transient grating has a potential application on investigating higher order nonlinear optical properties.