The effect of recycled oxide molar ratio on the size effect of geopolymer recycled aggregate concrete was studied by 4 different size specimens. The results show that the conversion coefficient of geopolymer recycled aggregate concrete cannot be used as specified in GB/T50081-2002 Standard for Testing Methods for Mechanical Properties of Ordinary Concrete. In this study, relationship of size conversion coefficient α and oxide molar ratio ε was worked out:α200=0.931-0.016×ε, α100=1.1086-0.0728×ε, α70=0.6716+0.0596×ε. The compressive strength of recycled aggregate concrete of 200mm, 150mm and 100mm are in line with the Bazant's theory of size effect curve, adopt the method of dimensionless can get polymer compressive strength of recycled aggregate concrete and oxide molar ratio and size parameters of the prediction equation of coupling effect, and it is concluded that the different conditions of recycled aggregate beneath gathered the strength of recycled aggregate concrete critical size and critical value.