Abstract: In the depression metallic open pit which adopts the semi-continuous transportation of truck-semi mobile crusher-belt，it is very difficult to determine the moving increment and period of crusher，because the complexity of existence of ore body and mining sequence.Took a mine designing for example，after adopted the theory of minimum unit cost，set up the cost calculate model and solved by computer，the best result was found.It is important for guiding production，and a calculation method for moving increment and period of crusher was found.

Key words: Depression open pit, Moving crusher, Moving increment and period, Mining sequence