A method to realize rapid nondestructive examination to the composition of milk by using Near-infrared Scattered reflection spectroscopy(1000～1700nm)was explored ,and quantitative relation of signal-to-noise (SNR) and measurement error of the systemwere analyzed. The feasibility of double light path compensation method and reference solution spectral autocorrection method against system drift during building model and measuring process were respectively researched and experi mentally verified. It was concluded that the reference solution spectral auto-correction method could effectively compensate system drift , and the predictive error in practice(ratio of Root Mean Square Error of Prediction(PMSEP) to mean of reference)of fat and protein reduce correspondingly 0. 14 % and 0. 72 % after correction with the method ,which was useful for improving long-time stability of the measuring system.