<p>The instability of natural and engineered slopes under diverse adverse conditions often triggers landslides, potentially causing significant casualties and economic losses, thereby necessitating a rational and accurate risk assessment of slope failure. Most of the existing studies have used the critical slip surface to assess the risk of slope failure, while slope inherently represents complex systems characterized by multiple failure slip surfaces (MFSS). The effective application of MFSS to the risk assessment of slope failure remains an open question. To address this issue, this paper develops an effective method for quantifying the failure risk at different locations on a slope in the case of MFSS by combining the limit equilibrium method, Monte Carlo simulation, and discretized mesh technique. To verify the accuracy of the proposed method, the risk value of slope failure calculated by the conventional method under critical slip surface is regarded as a benchmark to enable comparison with the calculated results of the proposed method. The proposed method is illustrated using two typical slope models. The results show that the proposed method can visually display the failure risk at different locations along the slope through color mapping, and highlight the high risk regions. Comparative studies have demonstrated that the risk assessment of slope failure based on critical slip surface may significantly underestimate the risk value, while MFSS can accurately and reasonably assess the risk of slope failure. The proposed method provides a novel perspective for a reasonable assessment of the risk of slope project failure.</p>