Raman spectroscopy ahs been used to investigates the structure of coal tar pitch hear-treated up to 3000\'C by using 514.5nm Ar ion laser line. Four critical temperature ranges were found on pyrolyzing coal tar pitch, which correspond to four distinct processes from disordered carbons to the well-orered graphite structure. The ramge of heat treat tem-perature(HTT) below 1000\'C corresponds to gas evolution during the pyrolysis of coal tar pitch.