The refractive index (RI) sensing performances of the single large gold nanocuboid and the large Au nanocuboid arrays were systematically studied by numerical simulation. The results show that the full width at half maximum of quadrupole resonance is much smaller than that of dipole resonance for large asymmetric Au nanoparticles. When the ends of nanoparticles become angular (quadrate ends), the quadrupole resonance wavelength will occur “red shift”, and the quadrupole resonance would possess higher sensitivity and FOM. The RI sensing properties (S≈787.72 nm /RIU, and FOM≈13.82) of Au nanocuboid arrays at quadrupole resonance are both larger than the respective parameters of single particle. The high sensitivity, large FOM and superior stability of the quadrupole resonance in large Au nanocuboid arrays would endow it with potential application in the LSPR biosensor.