The invention relates to a multi-channel terahertz 
wave modulation method. Incident terahertz 
waves pass through a terahertz wave 
collimator to become a collimated wave beam, the collimated wave beam sequentially enters multiple overlapped independent modulation channel modules to be independently modulated, each independent modulation channel module outputs an independent modulation 
signal, then all the output independent modulation signals are sequentially combined through terahertz wave channel combiners in the modulation channel modules and output uniformly from a 
system output opening, and 
clutter absorption devices are arranged in the independent modulation channel modules with the terahertz wave channel combiners. A 
system is composed of multiple terahertz wave modulator module units of different types in a free combination mode, and the purpose of increasing or decreasing the number of channels of modulation terahertz 
waves is quite easy and convenient to achieve; the function of performing 
selective modulation on specific channels (wave bands) is achieved, wave absorbers are used, in this way, disturbance of clutters or terahertz 
waves of non-attention wave bands is further reduced, and then the 
signal-to-
noise ratio is further optimized.