Through locating experiment and verification analyses conducted in pilot research sites for mechanized terracing in Wuzhuangyuan plateau slopes of Xifeng District and Songpan gully sides in Zhengning County,Xifeng City,a simplified mathematic model of multiple varieties and non-lineal is concluded for planning bulldozer terracing,that satisfies four targets: the less consumption of labor force,less quantity of terrace edge,more convenient for mechanized farming,and stable terrace.An earth-labor value with relevant models is established for calculation,namely,work quantity and weighted average-quantity of earth transportation.The output has been extended throughout the 6 counties/city of the project area of Gansu Component of China Loess Plateau Watershed Rehabil-i tation Project I,and achieved good effects.