In order to improve the design and calculation of anti-slide piles, the design method is proposed which can calculate anchorage depth of rigid piles based on bi-parameter mode of foundation coefficient and the corresponding formula is deduced in details. Based on these formulations，computation programs are developed for design calculations of anti-sliding piles and soil retaining piles for deep foundation pits. The example shows that this method is convenient, reliable and the final result can be directly obtained by simple trial calculation, so it has larger engineering application value. In case of the data of testing piles given, calculation results can perfectly coincide with measurements with foundation coefficients adjusted. When the obtained double-parameter is applied to other piles under the same conditions, the anchorage depth calculated will be reasonable and reliable.