Abstract: Transforming the continuous-time signal's independent variable substitution is the key knowledge point in the course of Signals and Systems.For the complex branch of the known substitute waveform,this paper gives the theory of drawing the self-variable substitution compound according to the time-shift—time-reverse—time-scale priority sequence according to the change of the independent variable.The case illustrates the application of the theory,and makes speech experiments with MATLAB,so that students can clearly understand and grasp the knowledge of signal independent variables.