Accurate measurement of refractive index is considered to be a deep understanding of the tiny physical or chemical changes in the media, such as the diffusion of toxic components in water, real-time analysis of the chemical composition of biological cells. All these analyte can be tested by small changes in the corresponding refractive index detection. Therefore, a detection solution of surface plasmon resonance refractive index based on Kretschmann structure is proposed. According to software simulation Mathematica, this paper firstly proposes to analyze the influence of change of refractive index of sample on the surface plasmon resonance absorption peak in Kretschmann model structure. And the trend of absorption peaks with the change of sample refractive index is obtained. On this basis, experimental model of Kretschmann is constructed, and refractive index measurements of mixed solution of alcohol and water are carried out. The results indicate that the reflection spectrum curve of sample can be effectively detected, and basically consistent with the theoretical analyses, and the sensitivity of the sensor is up to 86.88deg/RIU in the range of 1.33 to 1.36.The study has some benefits for the development of the refractometer based on surface plasmon resonance technology.