In this paper, a new method is proposed for the numerical simulation of erbium-doped fiber amplifiers (EDFA′s), which are modeled as homogeneously broadened two-level systems. The basic point of the method is to first solve out the population inversion along the erbium-doped fiber, then calculate other amplifier properties. This approach is highly efficient and accurate for the simulation of various complex-structure EDFA′s with arbitrary setup of modeling parameters. Fiber background loss or excited state absorption can also be considered. Based on the accurate measurement of fiber parameters, a comparison between the experimental and simulated results shows reasonable agreement.