To improve the sensitivity and the Q value of the photonic crystal refractive index sensor, a coupling structure combining the defect photonic crystal and the prism based on surface wave resonance theory is proposed. The sensing theoretical model is established by the layered transfer matrix method and the relationship between the Goos-Hnchen shift and the resonant wavelength is obtained, which can deduce the relationship model between the resonant wavelength and the refractive index of the sample detected. The SiO2-Al2O3-SiO2 structure is regarded as the defect cavity, which is replaced by the gold film in conventional surface plasmon resonance (SPR) sensor. Al2O3 is adopted as the absorbed layer, and then the resonant defect peak wavelength can be obtained and the dynamic detection of the refractive index of sample can be achieved from the shift of the resonant defect peak wavelength. The ethylene glycol is adopted as the sample detected and the Q value and the sensitivity of the refractive index sensing structure are discussed. The simulation results show that the sensitivity can attain to 3596 nm·RIU-1 (RIU is refractive index unit) and the Q value is 1087.7 approximately, which demonstrates the effectiveness of the sensing structure. The design scheme can provide certain theoretical guidance for high sensitivity and high Q value sensor design.