A surface plasmon enhanced refractive index sensor based on tunable liquid core photonic crystal fiber (PCF) covered with four gold-films. is proposed in this paper. The sensing performance of the PCF refractive index sensor is calculated and analyzed by using the finite element method. The chemically stable gold is selected as the coated metal material, which is used to induce SPR. The resonant coupling will occur when the phase matching condition is met between the surface plasmon polariton mode and the fundamental mode. The influence of the diameter of the central hole and the thickness of the gold film on the resonance wavelength and the confinement loss was studied. Numerical results demonstrate that the average sensitivity of the sensor can reach to 3200 nm/RIU, which can be used in the field of refractive index detecting.