The oxygen content of polysiloxane was characterized using the inert gas fusion infrared method， and the effects of moisture absorption， adsorbed oxygen， particle size， and sample weight on the oxygen content characterization results were analyzed. The results indicate that moisture absorption， particle size， and sample weight are the primary factors influencing the oxygen content characterization results. When the sample is dried， the particle size is <100 μm， and the sample weight is controlled within the range of 30~50 mg， the precision of the oxygen content characterization results for polysiloxane is <3%.