We studied the nonlinear refraction properties of an organometallic fullerene-C60 derivative fac- and mer- bis(1,2-diphenylphosphino) ethane (tricarbonyl)(η2-fullerene-C60) chromium by using Z-scan method.We also investigated the nonlinear refraction behavior of exited-state nonlinear optical materials and the switching between self-defocusing and self-focusing caused by the refrangibility of high excited state based on rate-equation theory.The transformation intensity was worked out,and the experiment was simulated numerically.The theoretical results agrees well with the experimental data.