Abstract: Coal maceral concentrates of high purity were prepared from four different rank coals by Density Gradient Centrifugation method. The formation of HCN and NH3 during macerals pyrolysis was investigated in a tubular quartz reactor at the temperature of 600 ℃～900 ℃. The results show that HCN is mainly produced by the secondary thermal cracking of coal volatile. It also shows that the HCN yield increases with temperature and decreases with coal rank for vitrinite pyrolysis. For three macerals from Pingshuo gas coal, the yield of HCN is not only related to their volatile content but also associated with the nitrogen functional group in different macerals. Macerals withmore pyrrole-type nitrogen could release more HCN at lower temperature. As for the formation of NH3, besides the volatile thermal cracking, the char pyrolysis also plays a important role. The yield of NH3 depends on the probability of contact between nitrogen functional group and hydrogen radical. On the experiment conditions, the NH3 yield decreases with coal rank for vitrinite pyrolysis. The inertinite of less caking has more nitrogen converted to NH3 than vitrinite and liptinite. The yield of NH3 during pyrolysis at 800 ℃ is maximum with 11.8% for inertinite and 5.2% for liptinite.