The system of non-invasive blood glucose detection by near-infrared spectroscopy was designed,and the influence of interface stability on the measurement was studied.It was determined by experiment that the optimal contact state appears when the probe just contact with the measured position entirely,and the optimal measuring time appears when it is 30 s after the probe contact with the measured position.Experimental results show that under the optimal conditions the root mean square error of prediction(RMSEP) of partial least square(PLS) calibration models are 0.56 mmol/L and 0.50 mmol/L respectively for two oral glucose testers.