Abstract： Based on the integration computational singular perturbation (ICSP), a reduced mechanism consisting of 24 species and 20 reactions was simplified from the skeletal mechanism. The reduced mechanism was validated using closed internal combustion engine simulator, and it was found that the reduced mechanism reproduced the important characteristics of dimethyl ether (DME) detailed chemical kinetic model, such as low temperature reaction, negative temperature coeffcient (NTC), the production and consumption of HCOOH and high temperature reaction. The results calculated from the reduced mechanism agree with that from the detailed one, which means that the reduced mechanism is suitable for the numerical simulation of homogeneous charge compression ignition (HCCI) fueled with DME. Besides, the poor applicability of reduced mechanism after trimmed by important index iuustrates the high simplicity of original reduced mechanism.