Alumina codoping can change the spectra of Er doped fiber amplifier (EDFA), which can be analyzed by Stark energy level splitting theory. Several types of EDFs with different alumina concentration were fabricated by modified chemical vapor deposition (MCVD) and solution doping method, and the fluorescence spectra of the alumina codoping EDF amplifier was explored. The investigation showed that alumina codoping result in a shift of fluorescence toward shorter wavelength. The absorption coefficients of EDFs with different alumina doping concentration was measured by cutoff method, and the result demonstrate that increasing the alumina concentration in EDF will increase the concentration of Er, which can improve the absorption coefficients of EDF and shorten the length of EDF in EDFA. High alumina codoping EDFA have wider and flatter gain spectra, which can be used in long haul wavelength division multiplexing (WDM) system.