In this paper,a novel approach of microwave frequency multiplicatio n by using a Mach-Zehnder modulator(MZM) and cascaded fiber ring microwave ph otonic filters (FRMPFs) was proposed and experimentally demonstrated.High order harmonics are generated thro ugh external modulation with large microwave signal,and cascaded FRMPFs can be utili zed to filter out the low frequency harmonics.The performance of the FRMPF is theoretically analyzed ,optimized and experimentally measured.By carefully adjusting the length of each FRMPF through tuning the optical delay line and optimizing the coupling ratio of the optical couplers in the FRMPFs,the desirable harmonic can be selected.In our experiment,two cascaded FRMPFs are used,and by u sing the first one,the first and third harmonics are filtered out while the second harmonic is filtered out by the second FRMPF,with only the fourth harmonic left after beatin g o n the photodiode with proper bandwidth.The experimental results show that by modulating a driving sig nal with frequency of 2.0183GHz,a signal with frequency of 8.0732GHz,which is four times of the driving frequency,is generated and the signal to noise ratio (SNR) is more than 13dB.