Abstract: The cumulative effects of contamination are an important factor for orbital life of GEO satellite. The molecular contamination from outgassing of non-metallic materials with respect to a GEO satellite is studied in this paper. A conservative outgassing model based on diffusion theory, line-of-sight transport model and contamination deposition model is built. The performance degradation of OSR and solar array is estimated by using view factor method with consideration of photochemical deposition effects. The prediction results indicate that RTV adhesive can produce severe contamination effects, while the effects of white paint can be neglected.