Abstract: Effect of solid material used in transformer manufacture on content of gases produced and dissolved in transformer oil base oil at low and high temperature was investigated. The results show that for base oil degassed, solid material bring no effect on gas content dissolved in oil at the normal（low）operation temperature, but negative influence is observed by solid material at local overheating temperature. For base oil without degassing, serious oxidation of oil can be observed by solid material, resulting in key gas content dissolved in base oil more than attention value required for the GB/T7252 standard both at the normal operation temperature and at local overheating temperature.