During long action of temperature and precipitation, ancient brick masonries were weathered. The experiment employed an environmental chamber to simulate natural condition. seven unsaturated freeze-thaw cases were designed to treat various specimens which are brick units, mortar cube, triple masonry and prism masonry. We carried out saturation degree measurement, compressive test and shear test to the various specimens in laboratory. The resules show that the saturation degree is one key factor to effect on material freeze-thaw resistance. The strength of specimens increaseed firstly with saturation degree and decreases after a certain saturation degree. The best compressive resistance of brick, mortar, and prism masonry was when the saturation degree is about 53%. Based on the weathering coefficient and specimen mechanical behavior, we suggested the evaluation standard of weathering degree for ancient brick masonry structures.