Abstract: Numerical simulation on preheating process of N₂O monopropellant micro-thruster was conducted as per orthogonal experimental design theory in order to study the influence of four factors-preheating power,surface emissivity,thickness of the combustor chamber and the adiabatic stuff-on the preheating process.Results of the simulation indicate that influence of the preheating power is most remarkable among the selected four factors,which is followed by the surface emissivity.Influence of the remaining two factors is not apparent.Preliminary results of preheating experiment under ground circumstance have testified the validity of the simulation model,providing a basis for further structural and experimental design.