In this paper, effects of the equivalence ratio (ER) and the secondary air on the gasification system were studied. The results indicate that as the ER varies in the range of 0.20-0.26, the low heating value (LHV) of the producer gas is in the range of 3.64-5.76 MJ/Nm(3). the carbon conversion is 55%-67% and the cold gas efficiency of the gasification system is 33%-47%. In contrast to the gasification without the secondary air, air staged process is a gasification method capable of increasing the LHV of the producer gas from 4.63 to 5.67 MJ/Nm(3). the carbon conversion from 65.5% to 81.2%, and the cold gas efficiency of the gasifier from 42.5% to 56.87%, while the tar content of the producer gas decreases from 13.96 to 5.6 g/Nm(3). There exists an optimum ratio of the secondary air. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.