In this paper, a novel hybrid passive component with a wavelength division multiplexer and a polarization insensitive optical isolator for an erbium doped amplifier is reported. The optimum design for hybrid component parameters by considering the characters of the hybrid component is presented. The hybrid component has the following features: insertion loss of signal light is less than 1.5 dB, the isolation of signal light is more than 42 dB, the insertion loss of pump light is less than 0.6 dB, and the 9 m diameter compnent is 45 mm long. We apply this hybrid component to an practical EDFA using the single forward pumping structure and achieve the small signal gain of about 30 dB, the noise figure less than 5 dB, and the saturated output power more than 10 dBm.