The low and medium frequency intensity noise of the erbium doped fiber laser (EDFL) is suppressed by using optoelectronic feedback. The factors affecting the intensity noise of the EDFL are analyzed by the rate equations. The importance of the phase of feedback signal in noise suppression are discussed by simulating and optimizing the feedback circuits. The experiment results show that the peak relaxation oscillation (about 30 kHz) is reduced to about 35 dB, at the low frequency band (below 20 kHz) falls to about 10 dB averagely and the relaxation oscillation peak moving to the higher frequency is suppressed. The excellent noise property indicates that the laser source has important applications in optical sensors.