Abstract: Researchers in eng ineer ing geo logy and geomorpho logy alw ays pay close attention to the rock w eathering rate. Howver, it is diff icult to f ind the quantitat ive results o f rock w eathering rates because they are ex treme ly low under the natural env ironmen.t Th is paper stud ies the relativew ea thering rate o f tu ff b locks form ing the ancient c ity w a ll of Quzhou. The w eather ing th ickness contrasts betw een the tuff b locks and the adjacent quartz sand b lock are used to ca lculate the tuffw eather ing rate on the basis o f the quartz sand block. It is found tha t from the construction time inM ing Dynasty to presen,t the tuff b lock has an averaged w eathering rate of 0. 086mm per year.