In order to optimize the extraction of total polyphenols from Terminalia chebula Retz. (TCR), the extraction technology of total polyphenols from TCR were optimized by using ultrasound assisted extraction with constant temperature and three-frequency (UAE—CT & TF). The reasons for high efficiency of this extraction technology were analyzed by comparative experiments and scanning electron microscope (SEM). The dynamic equation of diffusion for the total polyphenols was determined and verified based on the first Fick theory. Results showed that the optimal parameters of extracting technology were as follows, the concentration of ethanol was 60%, ultrasound frequency was 80kHz, ultrasound power was 180W and extracting temperature was 70℃. The extraction efficiency of UAE—CT & TF dramaticlly exceeded that of water bath oscillator extraction (WBE) (P＜0.001). The microcosmic structures of powders of raw material after being extracted by UAE—CT & TF were seriously destroyed from the analysis of SEM. The dynamic equation of diffusion for the total polyphenols extraction of TCR was determined based on the first Fick theory and ultrasound extraction dynamics. The verification experiment showed the logarithms of extraction time and power were all positively proportional to the concentrations of TCR total polyphenols. The technology of UAE—CT & TF was proved as a technology with high efficiency for extracting TCR total polyphenols.