Abstract: The crude fat was used as raw material, which was extracted from Nannochloropsis sp. by acid hydrolyzation. The pyrolysis characteristic of crude fat and its effect on the yield of each phase and the properties of bio-oil were examined at different temperatures in a bench-scale fixed bed reactor. In addition, the thermogravimetric characteristics of crude fat and all components were studied by means of thermogravimetric analyzer, and corresponding kinetic parameters were determined. The results show that both the yield of organic phase and the properties of bio-oil which is produced from the pyrolysis of all components are enhanced by the pyrolysis of fat. Moreover, with an increase in temperature, the yield of organic phase and the properties of bio-oil from crude fat and all components have same varying trend, and their best properties are obtained at 600 ℃. The content of oxygenated compounds in the crude fat including alcohols, acids and esters decreases and that of aliphatic hydrocarbon severely increases after being pyrolyzed. Compared with the pyrolysis of all components, the deoxidizing ratio and the content of carbon and hydrogen elements in crude fat after being pyrolyzed are higher, therefore the performance could be further improved with the increase of fat in the Nannochloropsis sp.. According to the kinetic data, the pyrolysis of crude fat and all components follows the second order reaction mechanism. The pyrolysis activation energy and pre-exponential factor are 64.34 kJ/mol and 2.94×10⁵ min^-1 for crude fat, and 48.13 kJ/mol and 2.96×10³ min^-1 for all components.