Chars from low rank fuels (i.e., brown coal and biomass) have attracted increasing attention as a promising candidate for catalytically reforming tarry material into light hydrocarbons and gases. The effects of heating rate and activation time on the preparation of char catalysts were examined. The catalytic activity of the char catalysts was tested for tar reforming during the pyrolysis of brown coal at different temperatures. The experiments of char preparation and tar reforming were conducted in a bench-scale quartz reactor. Results indicate that the char derived from a fast heating rate showed a much better activity on tar reforming than the one from a slow heating rate. The char with 3-5 min activation time gave the best catalytic performance, achieving a very low tar yield of 1.18 wt %. The increase in the surface area of char catalysts due to the char steam reaction did not always increase the catalytic activity of char catalysts. Raman spectra of chars revealed that the char properties (i.e., O-containing functional groups, and sizes of aromatic fused rings) played very important roles in determining the activity of char catalysts on tar reforming.