The dependence of nonlinear optical absorption and carrier dynamics on the thickness of chromium thiophosphate (CrPS₄) is investigated. Utilizing the I-scan system, we have observed the typical two-photon absorption (TPA) at 780 nm for three different thicknesses. The TPA coefficient, third-order nonlinear optical susceptibility Imχ⁽³⁾, and the figure of merit have been obtained by fitting the I-scan data. Using nondegenerate pump-probe measurements, the photoinduced absorption has been observed, and the carrier relaxation processes are phonon-assisted. This study provides deep insights into the nonlinear optical properties of CrPS₄, which is of great significance for potential applications in ultrafast optical devices.