An optical system based on Fourier transform near-infrared spectroscopy for nondestructive measurement of internal quality in intact fruit was developed. This system consisted of a light source, interferometer, fiber optical sensor, InGaAs detector, data collection card, and fruit holder. Quantification tests for sugar content (SC) and titratable acidity (TA) of 248 pear samples were carried out by using the multivariate calibration technique of partial least squares (PLS). The calibration model for SC and TA gave correlation coefficients of determination of 0.867 and 0.793, standard errors of calibration of 0.256 and 0.020, and standard errors of prediction of 0.320 and 0.019, respectively. Experimental results show that this optical system could be directly applied to fast quantification analysis for internal quality of fruits.