In view of the poor moisture-heat resistance property of traditional PET film (type 6021), PET molecular was modified by amine compounds for effectively improving the moisture-heat resistance property of PET film. By researching the compatibility of the appropriate antioxidant additives and amine compounds, ageing property of PET film was increased suitably. The optimum formula was designed by comparing with aging property decay of the 6021 film and moisture-heat resistance film (type A, B and C). At the same time, the mechanism of moisture-heat resistance and anti-oxidation also is researched. The modified PET film could be used in crystalline silicon solar cell industry for its high level of moisture-heat resistance as well as good mechanic property and electrical property.