We have discussed the kinetics of the capturing of freemajority tail by deep centres in semeconductors. We pointout that, the DLTS' signal is dicrectly proportional to the pulse width, if the DLTS' response region is restricted in the end of free-carrier tail vegion.This phenomenon may be used to measure the majority carrier capture cross section, in which the net shallow impurity concentration and the majority carrier capture cross section are both relatively wigh.