The concept of Initial Casualty Matrix is introduced. Using some probability distribution functions, the initial casualty matrix of masonry is determined. The dynamic method of seismic casualty assessment is established and then applied to the Tangshan earthquake data, with some conclusions drawn. The concept of Initial Casualty Matrix is ​​introduced. Using some probability distribution functions, the initial casualty matrix of masonry is determined. The dynamic method of seismic casualty assessment is established and then applied to the Tangshan earthquake data, with some conclusions drawn.