To investigate the feasibility of testing pork quality by terahertz (THz) spectroscopy nondestructively, refractive indexes and extinction coefficients of fat, muscle and skin of porcine tissue were collected by attenuated total reflection (ATR) mode in the range of 0.2～2.0 THz. The results showed that THz spectra of these tissues were different obviously in 0.2～1.6 THz. Water content was found to be a main factor affecting THz absorption of fresh tissues. The optical characteristic difference in THz band of different tissues could be utilized to identify tissue types rapidly and nondestructively. Moreover, it could be predicted that the pork quality could be tested nondestructively by establishing relationship model of THz spectrum and porcine tissue quality.