The refractive index sensing principle of tilted fiber Bragg grating (TFBG) and tilted fiber Bragg grating with surface plasmon resonance (SPR-TFBG) is provided. The transmission spectrum and reflection spectrum of TFBG with 8\O tilt angle and 1550 nm central wavelength are given. After that, refractive index sensing experiments are carried out using bare and gold deposited TFBG, respectively. The results prove that the deposited gold layer improves the refractive index sensitivity dramatically.