In order to analyze the sensitivity of factors influencing the stability of soil slope with soft interlayer under heavy rainfall conditions， based on the field survey data of the left slope of cutting in a section of Changsha-Xiangtan expressway and Saturated-Unsaturated see page theory， the numerical analysis model of the weak interlayer soil slope is established.And 4 internal factors， such as the dip angle of the interlayer， the interlayer thickness， the interlayer embedment depth and the interlayer number are selected to analyze the influence law of the various factors on the slope stability.The analysis results show that the critical value of the interlayer inclination of the left slope of cutting in a section of Changsha-Xian gt an expressway is 30°~35°.In the rainfall stage， the safety factor of slope decreases gradu-ally with the increase of rainfall duration.After rain stops， the safety factor increases slowly with the dissipation of infiltration rainwater， but the recovery rate is obviously lower than the decline rate.Under the heavy rainfall condition， the change of the inner factor of soft in-ter layer is the main factor that leads to the decrease of slope stability， among which the in-fluence of continuous rainfall scheme is larger.Whether or not the rainfall is considered， the sensitivity of the change of the internal factors to the slope stability is as follows：interlayer number＞interlayer inclination angle＞interlayer thickness＞interlayer buried depth.