Four methods including Morgenstern-Price method, Spencer method, Bishop method and Janbu method have been introduced for an analysis of the stability of a cutting slope at Shenzhen outer-ring highway under natural condition and saturated state by using a simulation software Geo-Slope, thus working out the safety factors for the most dangerous slip surface as well as its corresponding slope. Meanwhile, based on the field investigation and unbalanced thrust method, an analysis has been carried out, thus obtaining the stability factor for the most probable slip surface of slope. By comparing the results of numerical analysis and field investigation, the following conclusions are drawn: The slope is stable when its body safety factor in a natural state is greater than 1.0, approaching 1.2, while the slope is unstable when the safety factor of the slope is less than 1.0 under saturated condition. The position of slip surface obtained by numerical calculation and analysis is consistent with that obtained by field investigation and analysis, thus verifying the reliability of the results. Consequently, with such factors as the frequent rainwater in this area and a subsequent slope safety factor under saturation condition less than 1.0, it is suggested to support the slope in time to prevent the slope from losing stability.