Three oil shale samples from different areas in Huadian have been non-isothermally pyrolysed using thermogravimetric analyzer (TGA). The analyses were performed at different heating rates (10, 20, 40, 50, 100 K min(-1)) up to 900 degrees C with nitrogen as purge gas. The weight loss curve showed that pyrolysis of oil shale took place mainly in the range of 200-600 degrees C. It was attributed to decomposition of hydrocarbonaceous, material. At higher temperatures, the weight lessens due to decomposition of carbonates. On the basis of experimental data a model of pyrolysis kinetics was proposed. Kinetic parameters - activation energy (E) and frequency factor (A) - were determined by two methods: the direct Arrhenius plot method and the integral method. There was no clear relationship between activation energy and heating rate. The integral method of analysis gave lower values of activation energy than the direct Arrhenius plot method.