Abstract: Firstly the choosing method based on sort is imported into the basic ant colony algorithm and the new ant colony algorithm is applied to the optimization problem of the consecutive variable and the search for the minimum safety factor of the slope. The results show that the new ant colony algorithm is applicable to the few-variable numerical optimization problem and the search for the minimum safety factor of the simple slope , however the new ant colony algorithm is apt to the local minimum for the search of the minimum safety factor for the complex slope. The minimum safety factors gained by the complex method vary with the different initial multi-forms. One point of the initial multi-form is replaced with the local minimum gotten by the new ant colony algorithm using the substitution rule based on the minimum hamming distance and the complex method is apt to find the global minimum safety factor.