We propose a surface plasmon metal-insulator-metal (MIM) waveguide structure comprising a H-type resonator and an independent branch. The Fano resonance and optical sensing characteristics of the structure are examined by using finite element analysis. The findings reveal that the structure can achieve Fano resonance, and the maximum refractive index sensitivity and quality factor are 1078.33 nm/RIU and 1259.2, respectively. The effects of structural geometric factors on Fano resonance are examined, and independent changes of the Fano resonance line and wavelength are obtained. The suggested plasmonic MIM waveguide structure in this work has potential applications in integrated photonic devices and nanooptical sensors.