A high sensitivity dual-core surface plasmon resonance（ SPR）-photonic crystal fiber（ PCF） probe biosensor with a low refractive index measurement interval is presented. Using SPR technology to achieve the purpose of the test substance treat different refractive indices measured core loss by the measured change in resonance wavelength spectrum. Mainly in the central core is disposed a small air hole

to achieve the effect of the duplex transmission

acceleration of the SPR optical phenomena. The gold anon-probe is placed in the outer circular material channel to be tested

which not only facilitates the SPR reaction

but also has a simple structure and is easy to measure

and the working waveleng

th range can be adjusted. The experimental results show that the refractive index measurement interval is 1. 21 ～ 1. 25

the maximum spectral sensitivity is 11 000 nm/RIU

the resolution is 205. 9 RIU

-1

and the refractive index accuracy of the probe is 1. 8 × 10

-5

RIU. The fiber-optic sensing device proposed in this paper has great research value in biochemical sensing field.