Abstract: The complex antislide piles whose shapes like П or h have been applied to many slope protections. But it is difficult for many traditional methods to calculate the internal force of the pile,because the pile structures are statically indeterminate,the load distributions which acts on the piles are unkwown and the interaction between soil and pile is complicated. Its a feasible way for calculating the internal force of complex antislide pile using strength reduction finite element method. The assumed structure type and load distributoin are not necessary. So the results got with the method are authentic normally. In this paper,a complex antislide pile,whose shape likes П,located in a tunnel entrance slope was taken as a example. In the base of studying the slope stability,the pile internal force was calculated using the strength reduction finite element method. The interaction relationship between pile and soil and engineering control effect were evaluated. The results show that its an effective way using the strength reduction finite element method for calculating the pile internal force. Some results have reference values for protection design．