Non-isothermal pyrolysis of two kinds of Fushun oil shale with particle. sizes, <0.075 mm, 0.3 - 0.5 mm, 0.75 - 1.0 mm and 1.5 - 2.0 mm, has been investigated in stream (nitrogen) at the flow rate of 100 ml/min by thermogravimetric analyzer with a linear heating rate 6.8 K/min. It has been found that the temperaturee intervals of oil-generation from rich grade shale (9.8% Fisher Assay oil yield) and poor grade shale (3.9% Fisher assay oil yield) with particle size less than 2.0 mm are 400 -500 degrees C and 400 - 520 degrees C respectively. The kinetic treatment of the thermogravimetric data reveals that pyrolytic reactions of the two kinds of Fushun oil shale are both of the first order, but with different activation energy E and pre-exponential factor A in different temperaturee regions during pyrolysis. This is different from what was described in general terms as global first order reaction for oil shale pyrolysis by other authers. The kinetic parameters for pyrolysis of the two kinds of Fushun oil shale with different particle sizes were calculated by means of least square curve fitting, and the influence of particle size on pyrolysis was also discussed.