Abstract: Purespect near infrared transmittance spectroscopy with wavelength ranging from 643.26 nm to 985.11nm were employed to spectrally scan 100 calibration samples and 20 validation samples of Red Fuji apples ( Malus domestica Borkh.) for modeling to predict apple pH nondestructively.Influence of different pretreatment methods of spectral data and that of different wavelength selected on adaptability of the pH modeling were compared. The validation results of the prediction performance of the finally set model, with a correlation coefficient of 0.925 and RMSEC of 0.0395, showed that the performance of the established apple effective acidity model was stable and met the requirements of practical application.