Tower bricks deterioration due to climate influence accelerate ancient towers’ damage and decrease their life expectancy. Two representative ancient Chinese brick towers – Songyue Temple brick tower (about 1500 years old), and Fawang Temple brick tower (about 1200 years old) were selected as the subjects for a comparative study. In this study, it was found that they have common characteristics and similarities in geographic location, surrounding environment and climate, appearance and structure, the raw materials and brick manufacturing techniques, etc. X-ray fluorescence spectrometry was employed to analyze the material composition of the towers’ bricks; the mercury intrusion method was employed to test the brick porosity, brick pore size and pore distribution characteristics. The experimental results showed that an increment in porosity from 5th century to 8th century was the main index of ancient Chinese brick towers deterioration. About 30% of the porosity with small pore size in the 1000 nm diameter expanded to 10,000-50,000 nm. Therefore, to prevent small pore size (less than 1000 nm diameter) from expanding under the influence of the climate is the key of research to protect Chinese pagoda towers. The appearance characters of ancient towers because of deterioration of brick materials are also described to preserve ancient Chinese towers made of bricks.