Calcium in Renal Calculi is the main component for urinary calculus,therefore,it has important significance for fast determination of the calcium content of renal calculi.Attenuated total reflection-Fourier transform infrared spectroscopy（ATR-FTIR）technology is adopted for quantitative analysis of the calcium content both in 35 renal calculi and 46 preparation calculi samples.Spectral preprocessing methods and Monte Carlo uninformation variable elimination（MCUVE）are used for model optimization.The RMSECV and RMSEP are reduced from 2.62 and 3.04 to 2.06 and 1.88,and the correlation coefficient（Rv）is 0.966 when the spectra are preprocessed with multiplicative scatter correction（MSC）and MCUVE methods.MSC combined with MCUVE method can be used for improving the analysis precision of the calcium content by using ATR-FTIR technology,it also provide an auxiliary analytical methods for the cause analysis and classification of renal calculi.