As a kind of complex geological disaster, slope instability poses a serious threat to human life and safety, thus the prevention and reinforcement of slope is particularly important. In this paper, based on the three-dimensional stability analysis method of the slope reinforced by double-row anti-slide piles considering the soil arch effect, the “horn” three-dimensional rotational failure mechanism of the logarithmic helix is adopted to analyze the upper limit of the slope. According to the values of the geometric model parameters of the slope and the soil strength parameters in the actual project, the variation rule of the safety factor and the failure mode are analyzed. The stability of the slope is evaluated. The results show that the stability analysis method of double-row pile reinforced slope is simple and feasible in practical engineering, and the method also provides a certain basis for evaluating the stability of slope.