A novel gain-clamped erbium doped fiber amplifier ( EDFA) based on ring erbium-doped fiber laser is demonstrated. This new design provides a good gain clamp ing as well as a gain flattening without any gain flattening filter. 12m long low erbium doped fiberwas used as gainmedium pumped by 980nm laser diode (LD). The 30nm flattened amplification bandwidth was obtained with forward pump ing. By means of the 1520nm feedback laser the gain was clamped at 16dB. The gain characteristics against input signal power for both open-ring and the gain-clamped systems with differentVOA losseswere experimented, when the input power level increased from 240dBm to 10dBm, the signal gain was performed stabilization. The gain ripple was less than 0. 1dB from input signal power 240dBm to 0dBm by settling the VOA at 2dB where the amp lifier had a flatter gain spectrum. Small signal gain of 20dB was achieved at 1550nm with input power of 240dBm and the saturated output power could reach to 16dBm. Experimental results show that the signal gain was clamped and this gain2damped erbium fiber amp lifier could support a 40 channel WDM system.