As the temperature changes, the stability of bovine serum albumin (BSA) molecules’ interior structure may change. We measured the low frequency spectra of BSA’s solid sample heated to 298, 308, 328 and 348 K based on the technology of Terahertz Time-Domain Spectroscopy. According to refractive index curve and absorption coefficient curve, the refractive index of samples at different temperatures changes obviously, showing that the interior structure of samples changes; as temperature goes up, samples’ absorptive capacity has an obvious increase, but the sample at 348 K has a sudden decrease in absorption coefficient on average, showing that the samples have a denaturation. At the main time, using the theory of THz-TDS, we can get the relation that BSA’s imaginary part of dielectric coefficient and dielectric loss tangent change with frequency. Using Principal Component Analysis to reduce dimensionality, when the first three principal components reach to 98.69% of the amount of information of original data, we found that compared to refractive index, absorption coefficient, imaginary part of dielectric coefficient, dielectric loss tangent is most relevant to the temperature of the samples of BSA, with correlation coefficient reaching 99.76%. Combine PCA and fuzzy recognition, build BSA’s recognition models, and we gain a method to judge BSA’s temperature.