Abstract: A vector index effective model is used to analyze the effect of Er3+ on the nonlinear coefficient erbium-doped photonic crystal fibers. Through adjusting the structural parameters, including air hole radius r, hole-to-hole spacing Λ, refractive index of fiber core n and air-filling index ƒ, the nonlinear coefficient was simulated and analyzed and its change with structural parameters was obtained. The nonlinearity can be increased by doping rare-earth ion Er3+ in the fiber core, and it can changed at ease by varying the structural parameters so that it is feasible to obtain more applicable photonic crystal fibers.