In order to improve the sensitivity and linearity of the sensor, it is proposed to change the surface roughness of the optical fiber and the type of probe. Firstly, the D-type optical fiber with rough surface is prepared by the self-built wheel optical fiber side polishing system, and then one end of the optical fiber is coated with a layer of Ag film, which can be used as a mirror, so as to obtain the D-type optical fiber probe. Finally, when detecting the sensing characteristics of the probe, it is found that the change of the refractive index of the measured solution will cause the absorption of different energy, which will change the optical power received by the optical power meter. A series of experiments results show that the prepared D-type optical fiber sensor not only has very strong stability, but also has very good linearity. In particular, the sensitivity and linear correlation coefficient of the sensor with polishing loss of 18 dB are as high as 66.02 dB/RIU and 99.58%, respectively. The measurement and calculation of the accuracy of refractive index show that the accuracy can be as high as 0.000 04. The results show that the sensing structure has the potential to be widely used in biochemical sensing (such as COVID-19 pandemic) and real-time monitoring of environmental pollution.