This paper presents an active mode-locking optoelectronic oscillator (AML-OEO) utilizing a microring resonator. AML is achieved by integrating a Mach–Zehnder modulator (MZM) into a conventional OEO loop and varying the signal frequency applied to the MZM. Experimental results show that microwave frequency combs with repetition rates of 5.93, 29.65 MHz, and 59.3 MHz can be generated by fundamental, 5th-order harmonic, and 10th-order harmonic mode-locking, respectively. Compared to the phase noise of signals generated by a free-running OEO, that in the case of the AML-OEO at a center frequency of 14.64 GHz remains consistent across different orders of harmonic modes, with a phase noise of approximately -92 dBc/Hz@10 kHz.