Abstract： The stability calculation is the key to prevent and control the geological disaster of dangerous rock collapse，which is of great practical and prediction significance． However，the quasi-static method cannot depict the influence of factors as the shape and geometric size of the dangerous rock mass，the frequency and initial phase on the actual blasting vibration load． Based on conventional pseudo-static analysis and the slice method，a blasting dynamic stability analysis method considering size effect is established． This calculation program is compiled by using MATLAB． The results indicate that the calculated minimum stability coefficients of dangerous rock mass vary periodically with the initial phase of the blasting seismic waves． For a given calculation with specific parameters，the coefficients are proximate to those calculated by conventional quasi-static analysis． The relative difference of these two calculations is between 5． 1% and 8． 2%，which indicates the calculation method and program are reasonable and effective． When the number of slices is 1，the calculated results of the program are equivalent to those calculated by traditional quasi-static method． The method proposed in this study provides a reference for dynamic stability analysis and evalua- tion for dangerous rock mass．