In this paper,a metal-insulator-metal (MIM) type surface plasmonic waveguide (SPW)supporting multiple Fano resonances is designed,which is composed of a bus MIM waveguide with a stub resonator coupled with concentric double ring resonator (CDRR).The influence of coupling distance,stub height,and ring radius on Fano resonance is investigated with the finite element method(FEM).At the same time,the physical mechanism of multiple Fano resonances is analyzed according to magnetic field distribution.In addition,by changing the refractive index of the medium filled in CDRR,the application of the designed structure in the field of refractive index sensor is investigated.The results show that the sensitivity is up to 1 400 nm／RIU,and the figure of merit (FOM) is larger than 1 380.Finally,the slow-light characteristics of the structure are investigated,and it is found that the maximum group refractive index in the vicinity of the Fano peak is about 11.4 and the maximum delay time is about 0.076 ps.The designed waveguide structure has potential applications in the fields of nanoscale filters,refractive index sensors,and slow light devices and so on.