Most cultural relic architecture is in an outdoor environment, which causes ancient grey brick relics to be faced with serious environmental erosion and weathering problems. As a result, brick cultural relic architecture suffers physical and chemical weathering due to freeze-thaw cycles. In this study, we took grey bricks from ancient buildings as research objects to assess the effects of freeze-thaw cycle times on mass, void ratio and compressive strength. The bricks were subjected to 0,15, 30,45, 60 and 75 freeze-thaw cycles, and the microstructural changes in the bricks were observed using transmission electron microscopy (TEM). It was seen that, with an increase of freeze-thaw cycles, the mass loss ratio and void ratio increase while the compressive strength decreases. Micro-damage to the bricks was observed by TEM during the process of freezing and thawing,especially after the test with 75 cycle times. In addition, the chemical composition of the bricks was tested using X-ray photoelectron spectrometry (XPS), which showed that hydrolysis of soluble salt (e.g. carbonate) crystals is the main cause of the microstructural damage in chemically weathered bricks.