Abstract: Nonisothermal pyrolysis of two kinds of Fushun oil shale with particle asize 0.075mm,0.3-0.5mm,0.75-1.0mm and 1.5-2.0mm has been in-vestigated at the flow rate of 100ml/min in inert stream(nitrogen) by thermogravimetric analyzer with linear heating rate 6.8K/min.The characteristic values of pyrolytic kinetics of Fushun shales,their initial temperature of py-rolysis and the temperature at the maximum rate of weight loss etc.are obtained from the thermogravimetric curves,the rate of weight loss vs.tempe-rature curves and the conversion vs.temperature curves derived from experiments.It has been found that shale oil is mainly formed during pyrolysis of rich oil shale(9.8% oil yield of Fisher Assay) and poor oil shale(3.9% oil yield of Fisher Assay) with particle size 2.0mm in the temperature regions 400-500℃ and 400-520℃ respectively.Processing of thermogravimetric data reveals that the pyrolytic reactions of the two Fushun oil shales are both of the first order,but with different activation energy E and pre-expo-nential factor A in different temperature regions during pyrolysis.This is different from what was described in general terms as global first order reactions for oil shale pyrolysis by other authors in the past.The kinetic parameters for pyrolysis of the two Fushun oil shales with different particle sizes were calculated by means of least square curve fitting,and the influen-ce of particle size on pyrolysis was also discussed.