A high sensitivity of surface-plasmon-resonance(SPR) fiber optic sensor based on the wavelength modulation with tapered probe is studied theoretically and fabricated. The influence of different taper ratios (TRs) on the sensitivity and accuracy of the sensor is analyzed. It shows that with the increase of the TR, the sensitivity increases and the accuracy reduces. Considering the two indicators, the sensor has a good performance when TR is between 1.2~1.8. Based on the theoretical simulation result, the tapered probe is fabricated and the experimental system is set up. The experimental results show that the sensitivity of the sensor is 3.94 μm/RIU, which is well consistent with the result of theoretical simulation (3.90 μm/RIU).