Abstract: Based on the criterion of economic strapping ratio， surface model and columnar seam model， CoalDesign software system was used to optimize the final pit of an openpit coal mine in the Inner Mongolia. Some final pits were obtained under different technical and economic conditions. The case of final pit changing with cost and price was analysed. In practice， taking current technical and economic parameters as benchmark， when the price of raw coal increased by 10%， it resulted in raw coal yield increasing by 79%， stripped rock volume increasing by 115%， the stripped quaternary layer volume increasing by 6%， the boundary total volume increasing by 95% and the profit value increasing by 238% without considering infrastructure investment. When the cost of mining lowered by 10%， it resulted in raw coal yield increasing by 84%， stripped rock volume increasing by 123%， the stripped quaternary layer volume increasing by 65%， the boundary total volume increasing by 102% and the profit value increasing by 245% without considering infrastructure investment. The result showed that the final pit is influenced by price and cost greatly. Boundary analyses had an important reference value to making good decisions.

Key words: openpit coal mine, final pit, cost, price, economic stripping ration