A new method to measure pear fleshes liquid concentration using near-infrared spectrum analysis is presented. Using an indirect relative analysis method and through a lot of experiments we established the base model of the relationship between sugar solution spectra and its quality parameters. Based on the base model, we accurately obtained different concentrations of sugar solution. The source used is a stabilized white light, which gives different wavelengths. An experiment was conducted to monitor changes in spectra of sugar solution. The transmission peak was identified at 1 406 nm. Experimental results show that the measured value and the true value very consistent. The measurement sensitivity can be 0.05%, and absolute error is 0.002%.