Abstract: In space environment,molecular contamination condensed on sensitive surface is an important influence to the equipment characteristic.Based on dynamics theory of materials outgassing,this paper studied the processes of outgassing,transferring and adsorption experienced by outgassing molecules.Establish a model of multilayered system by analyzing the process of molecular contamination films.And make prediction to the influencing factor of transmittance of optical surface which has been contaminated.By measuring the transmittance of molecular contamination films produced from two nonmetal materials in different temperature and different sequence,the results indicate that the transmittance attenuation will increase along with the heating temperature.And the deposition sequence is an important influence to the optical performance.These conclusions verify the correctness of the model of multilayered system model.