Abstract: The n-heptane extraction residue (H-CT) from heavy medium and low temperature coal tar made in northern Shaanxi by n-heptane was reacted with formaldehyde. The product (P) was divided into n-heptane soluble (HS-P), n-heptane insoluble but toluene soluble (HI-TS-P), toluene insoluble but quinoline soluble (TI-QS-P) and quinoline insoluble (QI-P). The structure and composition of P were analyzed by means of GC-MS, TG-FTIR and FT-IR. The results show that P has more contents of TI-QS-P, oxygen atoms and a higher C/H atom ratio comparing with H-CT. The contents of HS-P, HI-TS-P, TI-QS-P and QI-P are 11.63%, 26.42%, 57.08% and 4.88%, respectively. HS-P and HI-TS-P contain mainly neutral components (mainly aromatics), few acidic components (mainly phenols), and some heteroatom compounds including O, N, S. TI-QS-P, with highly thermal stability, is rich in carbonyl groups, methylene bridge bonds and fused ring aromatic compounds. Besides, it also contains phenolic hydroxyl groups and aromatic ring substitutes.