The transient dynamics of a high speed rotor assembly of a twin spool engine undergoes blade-loss is presented in this paper.To simulate the sudden loss of blade,a concentrated mass unbalance is created and placed on the second impeller of the high pressure compressor.In order to modeling the continuous effect of blade-loss,a series of power functions are constructed to compared with the conventional discontinuous step function.Various transient analyses have been conducted during normal operations of the assembly with different parameters of loss.Analyses of the numerical results demonstrate that the transient dynamics of the rotor assembly is significantly influenced by the loss of the blade which results in impacting dynamics of the rotor.Big differences exist between the proposed power load function with the conventional step load and the proposed power functions will converge to the step function when the control parameters are set properly.Different combinations of blade-loss durations and power exponents will result in minimum amplitudes.