In the channel expansion project of a port in Guangxi，the cutter teeth of the heavy-duty cutter suction dredger “Tiankun” are worn out and fractured during the dredging operation of typical weathered sandstone，which affects the efficiency of construction. On the basis of analyzing the tensile strength and mineral composition characteristic indexes of the dredged weathered sandstone，we deduce the empirical relationship formula between the abrasiveness index of the sandstone in Qinzhou of Guangxi and the consumption of cutter teeth by the theory of dredged rock abrasiveness. This formula is used to predict the consumption of cutter teeth for digging weathered rocks by a heavy-duty cutter suction dredger. The research results reveal that 1）the integrity of the moderately weathered sandstone rock mass is good，with the uniaxial saturated compressive strength of 9-41 MPa and the geotechnical engineering property grading of the dredging as Level 12-13. In the dredging of the moderately weathered sandstone rock mass，the problems of abrasion and fractures of the cutter arm and teeth are prominent，and the moderately weathered sandstone is the key soil quality that affects dredging efficiency. 2）The improved theory of Schimazek’s F value is innovatively introduced to evaluate the abrasiveness of rock materials by comprehensively considering mineral compositions，mineral content，mineral hardness，rock particle size，and saturated tensile strength of rock. 3）On the basis of the theory of rock abrasiveness and construction parameters of dredging，the formula between the cutter teeth consumption of “Tiankun” per 10，000 cubic meters and the improved Schimazek’s F value is derived. 4）The absolute relative deviation between the calculated value and the measured value of the cutter tooth consumption of “Tiankun” per 10，000 cubic meters is less than 17.3%，which indicates good reliability and can provide technical support for rock dredging.