Abstract: Framed prestressed anchor rods are widely used in slope engineering.Considering the influences of supporting structures and anchor rods on the stability of soil slopes, the basic principles of the upper limit theory are analyzed, and the formula for calculating the safety factor of supported slope is deduced on the basis of plastic mechanics limit.The algorithm based on Matlab language is adopted to search the global optimal solution.Finally, according to the orthogonal design method, the influences of the internal factors such as slope angle, slope height and soil properties on the stability of prestressed anchor supported slope are discussed.It is concluded that the slope angle has the greatest influences on the stability of the prestressed anchor supported slope, following by the internal friction angle and slope hight, cohesion force, design value of thrust of supporting structures for the slope and soil weight, and the slope height, internal friction angle and slope angle have significant influences on its stability.