Abstract: The displacement mutation characteristics of monitoring points were chosen as the failure criteria of materials in the shear strength reduction method.In order to analyze the rationality of the chosen locations and the displacement modes of monitoring points,numerical models were founded for isotropic soil slope and joint rock slope,respectively.Some monitoring points were located in a slope.The relationships between the displacement and the reduction factor were analyzed.According to the displacement mutation characteristics of displacement-reduction factor curves,hyperbolic fitting equations were founded.It was shown that firstly,the correlation coefficients of the fitting results were close to 1,indicating that the fitting data were in good correlation with the monitoring data;secondly,the points on and below the critical slip line could be chosen as the monitoring points of displacement mutation criteria;the top of slope was recommended to be chosen as the monitoring point in the universal slope with the consideration that the top of the slope was sure to be below the critical slip line and its location was easy to be obtained;thirdly,all the three displacement modes could be chosen for monitoring.