Abstract: The excavation engineering is very special in round gravel area. The experience of option assessment for supporting and retaining structures needs to be summarized. On the other hand, many parameters such as the strength index of soil are uncertain. The partial coefficients of excavation stability cant be solved well using the reliability theory. This paper investigates many successful excavation engineering examples located in round gravel area. It arranges those relative parameters of retaining structures form selection. It calculates the several main stability partial coefficients of these excavation examples respectively. It establishes a data base finally. After having analyzed this data base statistically, this paper discovers the law of excavation retaining structures form selection. It obtains the several main stability partial coefficients by the lower limit method. The result shows that the overall stability partial coefficient is 1.3.The resist-overturn partial coefficient is 1.2.And the resist-seepage partial coefficient is 1.5.