Relation between PAHs and PCA in rubber process oil like TDAE which lead to environment-friendly rubber filling oil. Every day researcher studying about and testing different method to be able produce environmental-friendly rubber filling oil by different feedstock, hydrofining catalysts and process conditions accompanying by analyzing and comparing the PAHs and PCA content. Recent results showed that there was a non-ideal correspondence between PAHs and PCA content in environmental-friendly rubber filling oil by hydrofining process; the PAHs met the requirements of EU environmental protection laws and regulations when the PCA content was less than 3%.Otherwise, it was not necessarily, and the PCA content met requirements if and only if the 8 kinds of PAHs were below 1.0 μg/g or not detected. What's more, the operation range(reaction temperature) was wider than PCA when PAHs were regarded as environmental index. The empirical correlation yPAHs=0.036 3 xPCA3.186 6 for the determination of PAHs and PCA content in the hydrogenation process of the environmental-friendly rubber filling oil was established with the correlation coefficient of 0.982 2, which can predict the PAHs content through the analysis of the PCA content within a certain range.